It's flashy. It's unstoppable.
It is also single-use and impossibly scarce.
...Yup, it's going to end up sitting safe and sound in your inventory until the very end.
Games such as RPGs featuring an inventory system are prone to giving you items that are Too Awesome to Use. It could be an item that heals all your stats and makes you invulnerable for an extended period of time. It could be a special power that lets you fly, or a Status Buff that lets you destroy the universe with the snap of a finger. It could be a Superweapon with an extremely limited amount of ammo, or an ultimate sword that breaks after a certain number of uses.
It's useful, awesome, and practical — unfortunately, you're never going to see the item in use outside of maybe the last boss (as you wouldn't need it afterwards), either because you're afraid to waste such a valuable treasure and will be waiting for that one good opportunity to use it,note The pictured scenario is a classic example of a non-optimal yet necessary use of the item; the Megaelixer won't heal the two dead guys so, theoretically, it's a non-optimal use; or maybe because it simply pains you to imagine having it missing from your inventory. Of course you may save it until the last boss only to realize you can't use it during boss fights...
If a Too Awesome to Use item sticks around long enough, it can sometimes become Awesome, but Impractical as it gets outclassed by a much more efficient or re-usable item; in a game with Character Levels, it may also just become useless as your characters' stats outstrip the item's power. In any case, the item may just become useful in the Bonus Dungeon if one exists in the game.
Consequently, if there's an item duplicationglitch in the game, then of course you're going to be using it all the time.
A flamethrower is located in a hidden alcove. Despite being the strongest weapon in the game, the flamethrower is unique, only has 400 ammo and is best saved for the final boss.
Other rare items, like Red Potions and Pandora's Boxes, may also qualify.
And if you're smart you will never once use the Bazooka either to kill an enemy, even though it downs a lot of the otherwise Demonic Spiders in one or two shots. This isn't because ammo is scarce (quite the contrary), it's because the thing is simply too valuable for blasting open doors and cracked walls.
Chateau Romani in The Legend of Zelda: Majora's Mask restores your life energy and provides unlimited magic which lasts until you travel back in time to the first day. The downside? It can only be bought in Milk Bar at specific hours (namely from 10 pm to 5 am in the first two days, all night in the last), and that place can only be accessed after you get another mask. And the beverage is very expensive (200 Rupees). A seasoned player will prefer to drink it only when tackling a mission that may require a lot of magic (i.e. fighting Twinmold in the fourth temple).
Grandma's Soup refills all your magic and life AND doubles your attack power until you take damage (the only item in the game to do so), and you can do this twice with one bottle since she gives you two servings. Since getting a refill requires going all the way back to your house, an unpleasant task if you're in the middle of a dungeon, and since the game is relatively easy in the first place, you might opt to search for hearts and potions in grass and pots rather than using it, and you might beat the whole game without using it. (But you'll keep one with you anyway, since they're the best thing to have in your bottle.)
The Fill-Up Coupon for Beedle's Ship Shop. It automatically refills all ammo-dependent items in your inventory, but you only get one... Because the game is obligated to give you ammo in areas where you need them, and because the game almost always prioritizes ammo when you're not already full, you'll always feel more justified in just scavenging some ammo, rather than using the coupon. Because the coupon can also only be redeemed at one of the Ship Shops, even if you were completely empty on all arrows, bombs, and running low on hearts, there's still no reason to go out of your way to find Beedle just to use said coupon.
In The Legend of Zelda: Twilight Princess, you are rewarded with a bottle of Fairy Tears for collecting 20 Poe Souls. These not only refill Link's health completely, but they increase his attack power temporarily as well (unfortunately, only for 10 seconds at best). However, in order to get more than just the one, you have to take Link on a quest through the "Cave of Ordeals". But again, they are refillable and free afterwards, and beating the entire Cave lets you refill on Fairy Tears in 5 different areas in Hyrule. Rare Chu Jelly does the same thing, but good luck getting them in a crush of ChuChu or finding where they spawn.
In The Legend of Zelda: Skyward Sword, you can buy a certain potion that makes you take half damage for a while. You can also upgrade it to make you invulnerable instead. The period during which the potion lasts is rather long, and unlike the attack-boosting soup/potions from Wind Waker and Twilight Princess it is not canceled after being hit once. Once you get a certain other item, the potion duration is further increased. So you got an item that makes you invincible for a few minutes? Nope, won't use it despite its power, maybe because it ironically enough it too good and feels a bit cheap.
The Lightning in Medievil is the most powerful weapon in the game, but you have no way to recharge it if you run out. Most players never bother actually using it.
Castlevania: Symphony of the Night has any number of powerful, one-shot items that most players will hang onto "until the right time". But as the game is relatively easy compared to later Metroidvania-style games (and possesses what many consider the easiest Dracula fight in the series), that time will never come. On the second or later playthrough of the game, it is possible to obtain an item called the Duplicator, making those single-use items infinitely reusable; still, it's easy to see why many of them became equippable (and thus infinite-use) subweapons in later games.
Thanks to there being almost no hint of when it might be safe to use them, and being generally placed in arbitrary positions, the rarer-than-golddust save crystals in the Playstation version of the 3rd game ended up suffering from this for a lot of people. Previous games encouraged/forced players to manage their inventory by striking a balance between using medi-kits and using ammunition for the better weapons when confronting dangerous enemies. The crystals created a third thing to manage, and the more obsessive-compulsive players could find this pretty stressful.
The Rocket Launcher in the same game, whose ammo is obviously very limited, is best saved for the last two levels. To add insult to injury, you lose all your weapons and ammo in Area 51.
Large health kits are rare to find, thus players will opt to use the small health kits to recover just half their health, even if they are near death and would benefit from a full heal.
The Heart Pot you receive from Jenka in Cave Story: using it completely refills your Life Meter, and then it's gone. It does turn out that you can later go back to Jenka to get another anytime you want, but soon after getting the first one comes a longPlot Tunnel where you can't return to Sand Zone. On top of that, there are often sequences where you can't freely grab Heart Pots without resetting the level. And to a lesser extent, just going out of your way to go back to Jenka's house is a minor annoyance in general.
Spiral Knights has the Mist Tank, which you only get once after passing the tutorial and refills your Mist Energy once, i.e. the "currency" you need to enter levels and craft equipment. The community has, however, puzzled out an optimal method of spending the bonus Mist and the original starting 100 that will leave a new player economically competitive without having to go through the traditional starting grind. Eventually averted, as it is possible to acquire more Mist Tanks throughout the game, though rarely, before being changed to have no Mist Tanks at all.
The horror-based adventure game/first-person shooter/interactive movie Realms of the Haunting has a magic staff which has a very limited number of charges (something like 12 shots or so) and can't be recharged. It isn't noticeably more powerful than the game's other magic weapons, though, so you either never use it anyway, or use all 12 shots then forget about it. Sucks to be you if you did use it up killing common enemies, because it turns out this particular weapon pretty much insta-kills the otherwise very tough and annoying final boss.
Two items in Candy Box seem like this but one subverts it. The Berserk Potion makes the player move twice as fast and deal much more damage, but there's a finite amount that one can find in the game. As for the Chocolate Bar, you only obtain one before the post-game which makes it invoke this trope, but its one and only use is to upgrade your sword.
The Golden Hammers can automatically unlock a secret without having to do the challenge. You never use them. In the few challenges that really are exceptionally difficult (beating Boss Battles on Insane, for example), you can't actually use the hammers in the first place. Which makes them completely useless unless you're too lazy to complete the challenge yourself. Except in the PAL versions.
The heart containers in boss battles. They completely heal you, but there are only three, and they can't be used mid-battle, which often results in death after deciding to try and tank an easy boss at high damage.
BlazBlue: Calamity Trigger: The Barrier Burst gives you one shot at breaking free of a combo at the cost of lowering your defence for the rest of the round. For new players it is easy to fall into the trap of not using it because "it's not too late, I can still survive this combo and make a comeba—wait, what do you mean I lost?!" A good player has to learn when to bite the bullet and use Barrier Burst effectively.
BlazBlue: Continuum Shift and its Updated RereleasesContinuum Shift II and Continuum Shift EXTEND continue this line but separates the Barrier Burst into two different versions (and is also renamed to Break Burst). Additionally, everyone starts with one Break Burst and gains the second one once losing the round. The Break Burst (or at least the original one) will also halve "Guard Primers" needed to block guard-breaking attacks as well. Then we have the "Gold" Burst which can only be performed if the character is not being attacked and will launch the opponent high in the air and allow for follow-up combos. Finally, Astral Heats, already Awesome, but Impractical by nature in all but a handful of select cases, are now tied to the Burst Icons, requiring the use of one to activate on top of all the other required factors, meaning that if the Astral Heat whiffs or is blocked, the player could find themselves in a combo that they would've been able to Burst out of... if only they hadn't gone for the grand finale to begin with.
BlazBlue: Chrono Phantasma alters the Burst mechanics a bit—instead of being given a set number of Bursts, you have a Burst Meter similar to the game's spiritual precursor Guilty Gear that refills automatically after the Burst is used, though it refills slowly enough that one still has to be careful when deciding to use it or not. In addition to this however, Gold Bursts have been removed entirely and changed to a new Super Mode mechanic called "Overdrive." Using it also uses up the Burst Meter and forces the player to decide if they want to go on the offensive and use the Overdrive for possible better offensive capabilities or to Burst and break out of any combos the opponent tries. On the plus side, Astral Heats are no longer dependent on Burst.
The trademark Heart Artifact from Doom 3: Resurrection of Evil could stop time, turn the player invincible, and boost the damage of their weapon all at once. It was such a cool effect that the player is commonly tempted to conserve the artifact's energy and rarely use it, even though it could be recharged just about everywhere.
The BFG 9000 from all installments is likely to fall under this trope as well. The player is likely to use the BFG 9000 only rarely, though it only uses forty plasma cells per shot, because it's the biggest gun in the game. The "I can handle these with smaller weapons" effect comes to play even though in 75% of big fights, you can actually conserve ammo by using the BFG. Doom 3's/Resurrection of Evil's version of the BFG uses its own unique ammo, unlike the previous installments where it shared ammo with the more commonly used Plasma Rifle; thus making it even more restrictive to use.
First Encounter Assault Recon suffered from a form of this, where the three-weapon limit to the player's inventory meant that the rarer, more powerful weapons, like the multi-rocket launcher or the repeating cannon were often just left in favour of something simpler with more readily available ammo.
Half-Life: The Gluon Gun wastes away enemies with ease, even bosses, but drains your Nuclear Ammo extremely fast, so instead you end up picking and prodding at the enemies with your pistol.
Half-Life 2 turns the revolver into this: the gun can one-shot all infantry enemies if you hit them in the head, but you can only carry a maximum of 18 bullets at a time and ammo pickups average about one per level.
The second System Shock has Disruption Grenades, which are great against powerful enemies but always in short supply. Energy weapons, power armor, and implants could also qualify after a certain point, as there's an entire level full of powerful enemies and no rechargers at all, which can lead you to set aside some of your most effective gear because you're afraid of it running out of power and becoming useless.
The game has several special weapons that can be found once and only once. Typically they have something that sets them above their normal counterparts. Problem is, the game has weapon degradation, and - if left unmodded - no way of repairing damaged items. Which is why many players save up the special weapons, only to find out later on that they become useless against the heavily armored foes of the later game, who require heavier firepower to be brought down.
RPGs. As with all weapons in the game, they are realistically powerful, and thus (as the game's only rocket launcher) far deadlier than any other weapon you can acquire. The problem? The launcher alone takes up about 20% of your equally realistically limited carrying weight, and ammo is virtually nonexistent in the game: there are maybe three rockets you can find in the entire game, and that's if you really take the time to look.
In Metro 2033, military-grade rounds serve this function for the first 2/3s of the game. They provide a welcome edge against tougher mutants like Black Librarians, but are also the game's money system – meaning if you want that tricked out Kalash 2012 that's only available in Polis Station, you'd better choose your priorities. They lose this status toward the end of the game, where there are no more stores and powerful mutants are ubiquitous, so you can feel free to put them to good use.
Medics can, over the course of about 2 minutes, charge up eight seconds of invulnerability called an ÜberCharge. Of course, this leads to the age-old dilemma of when you actually use your ÜberCharge... Saving it can be vital, as beginning it mere seconds before the enemy initiates theirs will make it all but obsolete. So often, you end up waiting so long to initiate an ÜberCharge that you are killed before you can, and your Über meter is reset. It's a bit more bearable thanks to the existence of the Vita-Saw - a weapon that allows you to keep 20% of your charge upon death – but still.
This also applies to the Soldier's Buff Banner, which gives you and everyone near you a 35% damage bonus. To fill up the meter, you have to deal about 600 damage.
The first three games all feature a superweapon that the player must rebuild by collecting parts hidden in secret areas (the first game actually has two superweapons, but only one must be built). All four of these guns can clear entire rooms of enemies with one shot, but two of them carry only tiny amounts of incredibly rare ammunition (the Fusion Cannon having a total of eight rounds in the entire game), and another, the Chronoscepter, is limited to only three shots that can never be refilled without cheats. The worst part of this comes when the player realizes that the final boss of Turok 2 is actually completely immune to the ammo-starved Nuke superweapon, and that saving those precious few shots accomplished nothing.
Turok: Revolution multiplayer and single player gave us the Rocket Launcher's Swarm Bore and Nuke Attachments respectively. Nuke clears out the room, but then you would rather use them on That One Level or That One Boss. Swarm Bore... well...
First aid kits, even more so on Expert. Sometimes, people will absolutely refuse to use first aid to heal and will either be popping pills or just limp on and will only use first aid when the next knockdown is going to cause death. It's a common tactic on Expert to kill someone so they can respawn with more health and save a kit.
The sequel, Left 4 Dead 2, includes the M60, grenade launcher and chainsaw which are all very rare and come with limited ammo that cannot be refilled. There's also bile bombs and adrenaline shots, both of which are rare drops. Bile bombs can draw zombies away or even turn them on each other for a long duration, making them valuable during hordes, while adrenaline shots are the only thing in the game that give a speed boost and negate both fatigue and the zombies' slow-down attack. You can only carry one at a time, and it also means you cannot carry other kinds of bombs or pills (which are much more abundant). Thankfully, the areas where you must use these items are usually very obvious, but in certain maps (such as The Parish) where these locations are at the very end of the map, you're stuck holding onto them for several areas and unable to switch out.
The GEP gun is offered as an option to the player at the start of the game. Good enough to take out most bots with one rocket, it takes up a giant 8 out of 30 inventory slots, and ammo for it is relatively rare.
HE ammo for the Assault rifle later on in the game is partially susceptible to this, as while it offers Heavy Weapon power for a Rifle specialist, ammunition is fairly rare.
The PS20 is a one-shot holdout plasma blaster that has perfect accuracy even if you don't have any points in the relevant skill. It will kill just about any human enemy that you shoot in the head with it, and each one only takes up a single spot in your inventory space, but you don't find many of them, and it's hard to decide which of the many nameless mooks you battle to use it on. The Light Anti-tank Weapon is a one-shot rocket launcher that is guaranteed to destroy anything it hits directly, and also probably anything standing nearby. However, because it's only a one-shot gun and takes up four inventory spaces, it's impractical to carry around if you have other rifles or heavy weapons with you. Cue desperate thinking about how best to dispose of it along with some Inventory Tetris. On the bright side, the LAW was almost always found near giant military robots.
LAMs (grenades that can be attached to flat surfaces and then double as promixity mines) are extremely useful for blowing up doors and other barriers or for setting deadly ambushes. However, they are relatively rare, if not as much as some other items. You can use other, easier-to-find explosives like the GEP Gun to reduce the need even more. This can lead to sudden moments of anger when you already have the maximum of 10 LAMs in the inventory and come upon a new one in the field. There actually IS a point in the game where having loaded up on LAMs pays off, though. At a later point, they also pretend you'll need at least 5 of them for a mission (with a character charging you thousands of credits to buy some) but actually, any explosive will work. So in the end, outside that one scene, you'll probably still only use them to lay impressive ambush grids, lure your enemies into that, enjoy the show, then load a savegame and get past the obstacle without wasting LAMs instead.
In Deus Ex: Human Revolution you have multiple contenders for this, and frequently spend Praxis Points upgrading your inventory to keep it all in there.
The Heavy Rifle earlier in the game, which is almost useless without error-correcting augs, and later on the laser rifle or grenade launcher. Masses of space, no ammunition for the latter two, and completely unnecessary when you can headshot everyone with a silenced/laserguided pistol.
Those who pre-ordered or bought the applicable DLC pack will experience this through the grenade launcher; it can only be acquired about 2/3 into the plot and eats through boss health, but all ammo for it (save for the six grenades it comes loaded with) must be found, which means most players get little use out of it.
The Diamond tiles from Bookworm are just worth so many points, that using them in almost any situation feels like a waste.
The Spartan Laser in Halo 3, at least in the campaign. It will kill almost anything in the game with one or two hits, can hit multiple targets at once, and it's also really cool. The problem is, it takes a few seconds to charge up so it's a little hard to actually hit something, it only has 5 shots and can't be reloaded, you only get one two or three times in the entire campaign, and one of those times, you get it for the sole purpose of killing 343 Guilty Spark. So, you probably won't be using it much.
In the 2009 Wolfenstein the powerful experimental weapons you acquire early will have very little ammo available for scrounging until the weapons themselves become plentiful in the hands of the enemy. On the other hand, the Thule Medallion that gives you mystical powers appears even earlier, and energy refills are literally everywhere. Of course, the Medallion is an integral part of the game and story and you need to use it no matter what.
The Browning Automatic Rifle in the Medal of Honor games packs a punch and has great accuracy at long range, but has very limited ammo (practically no pickups). You can get by with an SMG in most situations.
Quake II has the Quad Damage and Invulnerability, items that give the player an enormous upper hand for half a minute. The problem is that they are inventory items, meaning you can activate them whenever you want to use them. However, they're so powerful and you fight off so few enemies at once in the levels, you'll keep the things in reserve throughout the game until the final boss. When used together, they turn it into a joke. It doesn't help that the game pretty much throws Quad Damages at you, making you feel kinda guilty for hoarding the two little Quads you found in the first hub throughout the whole game.
The Devastator from Duke Nukem 3D is a full-auto, double-barrel rocket launcher that's tiny explosions do as much damage as a single RPG round can clear out a whole room full of baddies in seconds, but it burns through its ammo supply very quickly and replacement rockets are fairly rare, so most players just hang onto The Devastator until it's time to fight the given episode's boss, which will go down in about 5-10 seconds of sustained fire from it.
Serious Sam's "I win" weapon is the Serious Bomb, which kills every enemy in an area, no matter how much health they have and it can be activated by merely pressing a button. Because of how powerful and handy it is, you'll usually be keeping it in reserve "in case" throughout the game. Serious Sam 2 and Serious Sam HD: The Second Encounter make this even worse because you have to take it out as a regular weapon before using it, meaning that even if you do want to use it, you'll have to determine if you have enough time or space to take the thing out and use it without being mauled, and by that time you've probably managed to thin out the horde enough so that you don't need the Serious Bomb anymore. On the plus side, Serious Bombs are the only weapon other than the knife and revolver that aren't taken away at the end of a chapter.
Borderlands 2 has the Golden Keys which unlock the golden chest in Sanctuary. Said chest can dispense items of a purple rarity, but because their stats are based on the current level of the Player Character, they can effectively be obsolete after a while, so some players would tend to save their keys for a high-level character. The keys can only be obtained through preordering the game, purchasing the Mechromancer pack and through codes being periodically distributed on Gearbox's Twitter and Facebook.
In Galactic Civilizations 2, it is possible to "get lucky" and find a rare Precursor battleship early on which is generally much stronger than anything currently out there. However, between fleet limits (a player at that point can generally only afford to field only that ship in a given battle) and a rather adaptive A.I., those ships may be held in reserve until they get surpassed by normal researched ships. Ironically, though, with the proper civilization traits, one can end up finding quite the number of such ships very early on.
In 4X game Space Empires V there is a special Ancient Ruins tech you may find if you colonise a planet, called Shield Imploder. It will bring down the enemy shields and cause damage to the enemy ship (Best description is the Breen weapon in Star Trek: Deep Space Nine), however it is rather weak at first, but eventually it will destroy with one shot ships relying on shields. So you end up keeping it secret so as not to let other players know you have it. A game can actually end before you get to the stage where it is a one shot kill weapon. Meanwhile it would have been quite good as it is to instantly remove enemy shields if you hadn't wanted to keep it a secret for later.
In X3: Terran Conflict, you acquire the Xperimental Shuttle from X: Beyond the Frontier at the end of a plot chain. It's the second fastest M3 and has 200 MJ of shielding. It's also one of two ships that can never be reverse-engineered (barring mods or cheating). You'll either tuck it someplace safe and never touch it, or use it very sparingly as a personal yacht.
The console-only (later ported to iOS) game Civilization Revolution gives you an ICBM once you build the Manhattan Project wonder. Unlike a typical Civilization nuke, this one can reach any city and wipe it off the face of the map without leaving any fallout. However, it's a unique unit that you only get once per game. You probably will end up not using it until the game ends.
In Diablo II the jewels and runes are items that can be put into special "socketed" items for stat bonuses, but can only be used once. They are just rare enough, and special items with stat bonuses drop regularly enough, that it makes one hesitant to use them instead of just waiting for another special item to drop.
Averted in Diablo III, where gems can be extracted from equipment they've been socketed into, either by paying the Jeweler a rather extravagant service charge, or by having the Blacksmith salvage the item (which consumes the item, but returns the gems).
For the longest time, perfect gems were the currency of choice in multiplayer games. This is due to the game suffering from Money for Nothing.
God of War has the Rage of the Gods in the first game. It takes maybe an hour or two of killing enemies to fill it up all the way, and once you activate it, you have about 10 seconds of mauling everything within 20 feet of you before it's gone. It can't be turned off if you activate it by accident either. From Rage of the Titans in the sequel on, there are orbs you can collect to refill the meter, and it can be turned off while active, averting this for the most part.
World of Warcraft has a lot of items like this, though Blizzard eventually changed them to be unreliable or useless against enemies over a certain level. Fortunately, many of them can still be sold to players that have less doubts about using them in a tight situation.
The Holy Mightstone, an artifact that a level 50 paladin receives at the completion of a lengthy quest chain. It provides a 10-minute buff to damage vs. undead when used, but it can only be used once and can never be replaced since it's a quest item, so the end result is that most paladins end up never using it. Sadly it's fallen victim to power growth in expansions. At level 60 it would turn you into an death-machine by practically doubling your offensive stats. At level 80 - not so much. It gives the same boost, but by now it's a 5-10% power-up at most.
Super Sticky Glue is an item you get from a quest in the Orc starting zone that allows you to immobilize the target. People always hang onto them in case they would ever really need one.
A similar case with the unique "Light of Elune" potion (which grants full invulnerability for 10 sec and then it's gone forever). You get it as a mid-20s quest reward; people still have it in their lvl 70 character's inventory.
A lot of the abilities with cooldowns over 5 minutes are seldom used except in times of utter desperation, waiting for that right moment... and sometimes in a dungeon or battleground run, never used at all. e.g. "Lay on Hands" (paladin) or "Recklessness" (warrior). Acknowledging this trope, Blizzard changed many of these skills to be somewhat less awesome, but with more manageable cooldowns, generally with the thought in mind that they should be available for every fight exactly once. Especially notable would be Shield Wall, a survival cooldown for warriors that used to have a 30 minute cooldown and make the user nearly invincible for its duration. Now it can be used every few minutes and still provides a significant damage reduction. Few abilities still exceed 10 minutes cooldown at this point, and many of those can be reduced significantly by talents.
Flasks used to be like this in the original game. While they provided outlandish buffs (such as increasing player health by 1200, which for most classes meant a 30% increase in HP - an incredible amount, particularly for boss fights), they were also notoriously difficult to craft. Obviously, you needed to be a high-level alchemist (which in itself wasn't that big of a deal — many players would grind alchemy as it provided access to expendable mana and health potions). However, crafting flasks also required Black Lotus, a ludicrously rare herb (initially at any time there were a maximum of four in the entire game, up to one in each of the zones they could spawn) that wasn't tradeable: you had to find it yourself (good luck!) and in order to be able to gather it, you had to be a maxed-out herbalist. Since herbalism was considered a primary profession (of which you could only have two), if you chose any combination of professions other than "herba-alchy", you could not make flasks, period. To top off the ignominy, flasks could only be made in one place in the entire world (later two), which was smack at the end of a high-level dungeon. When C'Thun was first killed, most of the player community had problems wrapping their minds around the fact that the victorious guild expended forty flasks on this single boss fight.
There are several temp powers with a limited amount of use, many of which are earned for or after a specific mission and will never be retrievable again. Not surprisingly, these usually get hoarded for emergencies, and are still waiting to be used when your own powers are so far beyond them that there's no point any more. In some cases they don't make any sense using even when you do get them, a classic example being the Loa Bone, which lets you summon a zombie. Cool for most people, utterly redundant if you are a Mastermind who can already summon zombies.
Some of these temp powers became so popular that when the developers added Veteran Rewards, a shiny badge for every so many months the player has been subscribed plus an item like a special costume item or a free character rebuild, two of the rewards each gave a choice of two temp powers that would become permanent on that character. The player can make different choices of which powers to take on every character they have. The Sands of Mu and the Nemesis Staff are the two most popular choices.
The Wedding Band hero-side springs first to mind. It granted a hefty resistance buff to all damage that lasted for two total hours of on-time (and maybe required an hour to get). Since it was only available to heroes, it quickly became the major target of villains and a fair issue of player-versus-player balance. The "Echo" version of the power now gives the same level of protection, but only lasts five minutes of on time, but can be stacked with the original version.
Similarly, there's the Inspirations you build up as you play, basically the equivalent of potions in other MMORPGs that can be used at any time to heal health, restore endurance, or give a number of beneficial buffs. The thing is, you rarely need to use them to win most fights so the tray quickly fills up with Inspirations you hang on to for tougher fights and emergencies that never come.
Many of the high-level powers take so long to recharge you can't use them in 99% of the fights. For example, an area-of-effect attack that lowers the defence, damage resistance and health regeneration of all enemies caught in the blast? Awesome. Too bad it has a several-minute recharge, and at the higher levels you tend to breeze through foes anyway, so the effect would barely be noticeable. Later on, many of the new sets had their "Tier 9" power not as Totally awesome, but usable much more often.
Kingdom of Loathing: Many, many one-use items, especially the ones that were available for a limited time in the past and most likely will never become available again.
Many of the semi-rares fall prey to this trope. This may be later averted when diving Fernswarthy's Basement, where every little bit of stockpiled resistance and HP buff becomes more and more necessary. The items you receive as rewards while diving Fernswarthy's do qualify, though.
Frosty's Iceball is an interesting variation. It does a large amount of elemental damage, even if you're low-level, and it isn't lost when used...the first two times. If you use it three times in one day, it vanishes. Getting it back is possible, but difficult, since it's a 20%-chance-drop from a certain boss in a multiplayer dungeon. The risk of accidentally destroying it by using it one too many times is a pretty strong deterrent against using it at all.
(Literal) Easter Eggs in Nexus War, because they can only be found once a year, at Easter, and have variable effects which can't be determined before use. Later versions did this with Valentine's Day gifts as well.
zOMG! has the power-ups (Superchargers to restore partial health & stamina, and Ring Polishers to temporarily increase the strength of your rings). Players get a couple of these from early quests in order to try them out. You can buy more, but the cost is in Gaia Cash, which requires spending real money (as opposed to Gaia Gold, which you can earn in at least a hundred different ways). Therefore, the power-ups earned as quest rewards can become Too Awesome to Use. Recent updates have attempted to mitigate this: power-ups are now rare loot drops, and power-ups bought from the store can be resold on the site's marketplace, which uses Gaia Gold as its currency.
EVE Online has several extremely limited-run ships that were/are only handed Uout as a result of one-time events, such as the Alliance Tournaments. Since being able to say that you destroyed one of the five, say, Imperial Issue Apocalypses in existence is cause for immense bragging rights, the result is that these ships sit in their owners' hangars, never actually being flown.
The Tiger Shark, one of the most powerful pieces of food in the game. It heals more Life Points than any other fishnote Except the Baron Shark (also very rare), which heals slightly more, but with a delay, and it can even boost your life above its normal maximum. Of course, it can only be obtained with a near-maxed fishing level, requires a near-maxed cooking level to be edible, can't be traded with other players, and it's very rare, obtainable only through the Fishing Trawler minigame at an average catch rate of roughly one tiger shark for every hour of trawling.
The Ancient Warriors' equipment used to be this. While chaotic weaponry and Nex armour surpass or at least rival them, Ancient Warriors' equipment has been around much longer. Ironically, the armour regained some popularity when they are given high damage soaking, as while they degrade into dust very quickly, individually they are cheaper than Nex armour and is less of a loss in high stakes PvP.
In the "Sizzling Summer" promotion, players who had membership during a certain time period could redeem their fate cards for up to four extremely useful items, particularly the instant-kill darts, which could only be used on NPCs. The special items were removed from the game in the beginning of 2013.
Final Fantasy XI is absolutely the king of this trope. Most items are extremely painful to get in this game and many of them are single-time use only. Many of the items below were extremely powerful when they were made available; their use has diminished somewhat since the level cap raise.
Phantom Tathlum — mediocre one-time use multi-class throwing weapon that is dropped by a Notorious Monster (NM). The only reason to own this item is the rather useful +2 INT that it provides when equipped in the throwing slot. To spawn the NM, one must trade an iron ore (uncommon item) to a ??? marker that randomly pops up in a high-level zone every 15 minutes. The item drops approximately 15% of the time. Woe be to you if you accidentally push the "Use Ranged Weapon" button.
Ambrosia — this nectar of the gods provides +7 to all stats for 4 hours. To obtain this item one needs to a) travel to a specific zone to kill enemies that have a 5% chance of dropping a specific craft item, b) travel to vendors that may or may not sell specific crafting supplies based on whether players control certain regions in the game, c) have nearly 100 cooking skill, d) cook a Cursed Soup item, e) travel to an high-level end-game zone where a Notorious Monster spawns every 2~6 hours and has a 33% chance to drop a 'Oblation Abjuration' item, f) give the abjuration and cursed soup to an NPC to receive the "Ambrosia" item. The item buffs used to not persist through death.
Amrita — a drink which restores 500HP over 5 minutes. Follows the exact same creation process as the Ambrosia.
The Abyssea expansions have Primeval Brew, an Abyssea-only one-use item that boosts all your attributes to 999, your HP and MP to 9999, gives you a 500 point HP and MP restoration and 50% TP every three seconds. The downside: It costs two million cruor (An abyssea-only currency that can't be traded for and is usually only gained in small amounts) to buy just one three minute dose. However, it goes from Too Awesome to Use to Awesome, but Impractical once you defeat the final boss of the Abyssea expansions, when you a receive a key item that drops the cost to a somewhat more palatable 200000 cruor. To put the Brew's power in perspective though: With normal abyssea buffs, an average damage-dealing job can do 3000-6000 damage with one weapon skill on a normal opponent. With a Brew-buffed Corsair with an Armageddon, one can do 75000 to 99999 damage with one weaponskill. And with the 50% TP/3 second gain, one can perform a weaponskill every six seconds.
Billy Vs SNAKEMAN has Consumable Kaiju Drops. They are moderately rare items that give a small bonus as long as you have at least one in your inventorynote multiples don't stack but a massive bonus if you consume one. Naturally, the consume bonuses of such items are far less than the cost of obtaining them.
The Lord of the Rings Online occasionally gives consumable items as quest rewards or as part of the in-game lotteries that are bound (can't be sold or traded) and give a significant benefit (stat boosts, or increasing the amount of XP you earn, or counting each kill as double for slayer deeds) for a strictly limited time. In most cases you can buy more of these in the Turbine Store, but in practice you're usually better advised to save your turbine points for stuff that's even better, like items that permanently boost your stats. Limited inventory space does help provide an impetus to actually use the items while they still confer a significant bonus, though (+150 HP is a game-changer when you normally have a couple hundred; by the time you reach the level cap it's a pretty pathetic tank who isn't boasting at least 10k).
Prior to the Generation 6 update, SD Gundam Capsule Fighter had the OC 100% chip, which allowed players to level up their units to the next Over Custom level without fail, though only to OC 5. However, you could only obtain them via giveaways and events, so you'd only get 2-3 at a time and with dozens of Mobile Suits...
In Marvel Heroes, various heroes' ultimate skills take a looong time to recharge, up to 20 minutes. You aren't just gonna use Deadpool's Server Lag to annihilate this group of mooks right? Definitely not even on this sub-boss or elite mob. Maybe not even against this stage's boss, what if you'll need it for the next one?
Star Trek Online has the game's secondary currency, Dilithium. Unlike Energy Credits, Dilithium has to be "refined" once you obtain some (there are plenty of ways to obtain them, thankfully), but you can only refine 8,000 a day. What makes this worse is that there are dozens of items that absolutely need Dilithium to obtain, the worst of which are the Reputation items, which cost anywhere from 5,000 to up to 45,000 an item. Not only that, but trying to build your fleet up requires Dilithium, so many budding fleets tend to get wiped out because members absolutely refuse to contribute because they absolutely have to have a certain item.
Lucent Heart has two different healer type skills that are this. While they do boost damage by a sizeable chunk, they do not increase defense, have lengthy cooldowns, and force the user into melee. This is impractical for such classes.
A few heroes in Dota 2 have powerful area of effect ultimate abilities that have massive cooldowns. Many players would rather let themselves or an ally die than use these abilities in any situation other than a 5v5 teamfight - indeed, part of the game's massive learning curve is figuring out which situations it's okay to use a two or more minute cooldown ultimate in.
The Grenades in Metal Slug are rather powerful. You'll want to keep them the first time you play the game, thinking you're going to find a good use for all that power... The game soon obliges, and you'll usually end up wasting those grenades when you get killed. Of course, you get a fresh set on your next life, and hopefully a little extra insight on how things work in the game.
P-wings in Super Mario Bros. 3 gives you infinite raccoon flight. This game also had some other items that fell prey to this effect, like the Hammer Bros. Suits and the Tanuki suits. They were just too cool and rare to use anywhere. They're more usable in the All-Stars remake, where you can save items and regain items earned from beating worlds, meaning you can easily farm P-Wings by repeatedly beating World 1. The same goes with Lakitu's Cloud, which allows you to automatically skip a single stage.
Mega Man 9 gives us a few of these, with shop items that are expensive, or of which you can only have one at a time. Eddie Call can give you items, including 1-ups. The M-Tank acts like Final Fantasy's Elixers: it refills your Hit Points and all your Weapon energy. But the biggest user of this trope has to be the Guard Power. It grants double armor for 1 level, but though you'd be tempted to use it against the Bio-Devil twins, you'd be far better off using it against the final level's Boss Rush and Wily's 3-stage battle.
Mega Man Zero's Cyber Elf system. Offering tons of one use power-ups that have a personality and die once you complete a level. This is averted in Zero 3 with Satellite Elves; but with so many Elves and abilities how could you limit yourself to just two?
Bunny Must Die! Chelsea and the 7 Devils has both Bunny and Chelsea dolls. Bunny dolls are optional uses when Bunny bites the big one, and can reload the entire room with Bunny at full health. Chelsea dolls are automatically used when Chelsea gets slagged, and restore Chelsea to full health and Mana. Naturally, players will preserve as many of both of these as possible for the Final Boss battles in each game — Chelsea for Bunny, and Septentrion and Bunny and Dechronos for Chelsea.
In the second and third Jak and Daxter games, it took so long to charge up your Dark Eco meter to use your Dark JakSuper Mode, and you could use up your entire meter in one kill-everything-on-the-screen spray of purple lightning (the same applied to the Peace Maker, a BFGlightning-death-cannon-thing due to its extremely low ammo capacity). As a result, it was extremely rare that you'd bother using either...until the end of Jak 3, in which the end boss was kind enough to provide Light and Dark vents, permitting you to Super Mode with impunity.
In The Lost Vikings and its sequel you can find an item that kills every enemy on the screen. However, this item rarely comes into play as you can usually take out your enemies easily enough with your normal attacks.
The question skips in The Impossible Quiz. You do actually need to stockpile every last one to get past the last question. Muhahahaha.
In Mario Kart 8, the Super Horn. Sure, it can hurt all other racers in a wide radius, and destroy incoming red shells to boot, but its ability to destroy spiny blue shells means that if you're even close to first place, it's probably not going anywhere.
The heroes in Warcraft II are almost always Too Awesome to Use, as in most missions if they die you lose the mission. Only the human side has healers, auto-healing doesn't exist, and you don't always have healers in every mission, so most of the time you keep your hero locked up tight in your base where no one can hurt it, so that you don't accidentally lose the mission by getting them killed. The expansion Beyond the Dark Portal made the heroes into souped-up versions of the regular units, so you might be tempted to use them; in vanilla Warcraft II, they're weaker than regular units and far too easily killed to ever be risked in battle. Except when you really need that spell only the hero can cast.
Heroes were a big problem in most early RTS games, including Starcraft and Age of Empires. Generally the heroes only found use if they were either expendable or in a no-production mission. Newer games, especially Warcraft 3, combat this by making Hero Units respawnable and able to be customised and levelled up.
The Eldar's relic unit is the Avatar of Khaine, a Physical God with the most health of any unit, very high damage, and makes nearby units much more resistant to morale damage. And yet many players (and the AI) will keep it inside their base, where it can't get into combat. Why? Well, because it also makes every unit build faster, and increases the cap for for infantry and vehicles.
You can call in Veteran units at any time in the campaign mode from the previous missions. You never will because you might need them when the AI decides you have won too many games in a row and starts to rush you with an unbeatable amount of units. Any recent DOW game has had the same problem for me.
In the second game, the artillery strikes are hard to get and only work in incredibly specific situations (Tank traffic jams) but can win you the game. Averted when you play a longer game mode though, as you will probably get enough resources to use these strikes and other support abilities multiple times.
The Death Star if you played as the Empire. Though costly and time-consuming, building one immediately helped your popular support, but if it left the sector, all the planets would slightly favor the Alliance. Furthermore, if you destroy a planet or if your Death Star is destroyed, you lose popular support throughout the galaxy. But if you've found the Alliance headquarters and have already captured Luke and Mon Mothma, it's a quick win.
Conversely, the Alliance has Luke: High in all stats except Diplomacy and Force-sensitive, his Force powers meant he could level up with a certain number of missions. If Vader or Palpatine were present, it would be that much quicker. (In fact, if you have Palpatine under blockade, you can have Luke powerlevel by sabotaging everything on the planet, and then abducting Palpy.) But if Luke encounters Vader or Palpatine, there is a chance he'd be captured instantly, one third of the Imperial victory conditions. But you need to encounter Vader to learn that Leia's Force sensitive.
There's also the fact that the game randomly selects who will be Force sensitive (aside from the canonically required characters) each time you play. While there's no guarantee that your Force-sensitive characters will be any good, if you'll lucky enough to end up with a Force sensitive Thrawn, for example (who has naturally high stats to begin with, and Force training increases all stats), you'll probably not want to risk losing him. Especially since, unlike Palpatine and Vader, he can be killed in battle, thus eliminating the possibility of a rescue mission.
Some ultimates in League of Legends have this issue. Galio's ultimate, with a huge cooldown of over 2 minutes, is a channeled vortex that taunts enemies towards you, then explodes for massive damage. Locking down the entire enemy team and drawing them together can turn the tide of a fight and possibly the game, so you may end up never using it because the perfect opportunity may arise just 30 seconds later...
Purple Pikmin. They have ridiculously high attack power and can stun enemies if they land on them, but they incredibly slow and lack any immunities like other Pikmin types, and on top of that they can only be created through rare Candypop Buds underground, unlike the primary Pikmin which come from Onions. Considering most bosses ingame either rely on a specific immunity or being able to get out of the of an attack quickly, some players prefer to use Red Pikmin than risk losing their Purples, due to only having slightly lower attack power than Purples, but are much quicker and plentiful. Also, there's the issue of requiring 100 Purple Pikmin to lift a dumbbell in Wistful Wild, which encourages players to save them until reaching that part.
There's also Bitter Spray, which completely immobilizes enemies and makes even the toughest bosses complete jokes. To balance this out though, they are much rarer to come by they Spiecy Spray, which just powers up a Pikmin's attack and speed, and the berry plants needed to make them are often in inconvient locations. As such, most players just save them for when they're really in a jam and there's no other way out. (Usually when faced with Spotty Bulbears.)
When playing as Vegas or Pointman in Audiosurf, players may hold on to a paint or sort powerup until they get a large combo or the end of the song so they can get clean finish. Overfills that could have been avoided by using one of these powerups will ruin their plans, however, due to losing all power ups you were carrying when you overfill.
NetHack: In the late game, certain expendable items do become almost useless - namely scrolls and potions. (No need to hurl potions of paralysis at a monster when you can smite it with Excalibur, after all.) Almost, because you can dip potions and scrolls in water to blank them out - and with the proper tools, bottled water and blank paper can be some of the most useful tools in the game.
One playing the NetHack variant Slash'EM may come across the Houchou, an artifact-level spoon. Throwing this spoon at a monster results in an instant kill, after which the artifact is destroyed. Slash'EM mostly averts this trope, though, because just about every player has their own idea of which single creature in the game deserves skipping.
This is especially true in Linley's Dungeon Crawl, as beneficial potions and scrolls are relatively common and safe to identify by trial-and-error (and it is easy to end up facing half a dozen rampaging orcs with three hit points left).
Being based on the same principle, but adding in an overworld and the ability to buy storage houses... let's just say it is very common to have a ginormous amount of these in Elona.
Summon feathers in Chocobos Dungeon allowed you to replace your partner with far more powerful summon creatures. This meant calling to your aid allies that could take down the game's bonus boss singlehandedly while taking only pitiful damage in return. The downside is that, should they actually die, you lose the feather you likely spent hours trying to get your hands on. A random summon feather takes away that risk but doesn't give you the option of selection.
In Castle of the Winds, you randomly find magic wands that can cast all kinds of spells, even the room-clearing Ball spells, with as much as a dozen charges. Even if you do put one in your belt, you'll probably forget you have it.
Spells in The Consuming Shadow packs quite a punch in battle and have several beneficial uses outside combat. The problem is that they put quite a drain on the Sanity Meter, and you really don't want the protagonist to go insane before the end-game, especially since he can't cast spells with too low sanity.
Secret of Evermore has two super-rare weapons: The bazooka and the call bead. The former is a projectile weapon that deals tons of damage and can be loaded with three kinds of ammo, except said ammo is so rare and expensive you'd normally never fire it. The latter summons an ally who launches a very powerful spell, but since there are only so many call beads in the game you'd never use them. However, thanks to a couple of Good Bad Bugs, the Cryo-Blast rounds (Which happens to be the best ammo) don't deplete as you fire them and you can get infinite call beads thanks to a glitched event flag in Nobilia.
There are a multitude of items like this in Pokémon:
The Master Ball is probably the most famous example, since it can catch any Pokémon regardless of how strong it is. However, you usually only get one during a playthrough, though it's possible to get more of them via the lottery, trading, or exploiting cheats.
Certain healing items, such as Max Revives, can heal every Pokémon in your party to full health but can only be found once or twice in the game. In most games, there's only one legal way to get Sacred Ash (two in HeartGold/SoulSilver), which is usually by catching Ho-oh, who will be holding it... but the item's power is ridiculously awesome - it can revive all of the Pokémon in your party to full health (albeit only on the field), something you can normally only do by visiting a Pokémon Center.
Ethers and Elixirs can't be bought in stores, and are only found on the maps. Therefore, they are usually conserved for the right time. In the later games, Mysteryberries and Leppa Berries had the same effect, but you could replant them for more, thereby rendering Ethers yet another useless thing that garnered lots of cash.
Rare Candy, a free level-up, is another example. However, since the higher a Pokémon's level is, the more experience it needs to level, saving them for later leveling lets you get the most bang for your buck.
Items necessary to evolve certain Pokémon (Elemental Stones, King Rocks, and the like) have always been notorious for being rare and hard to find. Most of the time, you can only find a few on the ground, get them as gifts from characters, and very rarely, find them carried by wild Pokémon. Pokémon Black 2 and White 2, and Pokémon X and Y after them, made some of them more readily available so long as you fulfilled certain conditions.
The games have a large list of TMs (items that teach attacks to Pokémon), some which can be bought at markets and Game Corners, others that you only get one of... ever. This might not seem so bad until you realize that TMs can only be used once, at which point they disappear forever. And if you're the kind of Trainer that switches up his/her team a lot, you may have just wasted a strong attack on a Pokémon you'll never use again. Earthquake is a particularly big offender, given its high power, high accuracy, lack of negative side-effects, useful typing, and nearly everything being able to learn it. Worse, since only fathers pass down TM moves, the player is discouraged from ever using one-of-a-kind TMs on female or genderless Pokémon. This is no longer the case from Generation V onward, since TMs are now infinitely reusable.
Time Flutes in Pokémon Colosseum instantly purify any Pokémon, thereby giving them an extra move and whatever experience they should have gained through battle. However, there's only 3 throughout the entire game, and one of them comes from beating Mt. Battle. One is also required to purify the final boss's Tyranitar, as it cannot be purified under normal conditions. As a result, those unable to conquer Mt. Battle have only one Time Flute they can use for whatever Pokemon they want, adding to the stress of determining who it will be used on.
Pokémon Black and White adds Gems, which grant a whopping 50% power boost to a move of the same element, but they're one-use, which means that after that initial blaze of power, your Pokémon is stuck with no item (although this is a good time to follow up with Acrobatics). You have to decide if the one-time boost is preferable to the constant 20% boost you'd get from a Type-enhancing item of the same element. These Gems are rather rare (only being found in certain spots or randomly-appearing dust clouds in certain areas), so it's more useful to use them in situations like Link Battles, the Battle Subway, and the PWT, where held items are restored between matches.
Certain Berries reduce super-effective damage from a certain type, restore health, or raise a stat when at low health. They're consumed upon use. Especially problematic in Generation V, where the only way to obtain those berries easily (or at all) are on the Dream World website, or only obtainable from certain Join Avenue shops. Again, it's better to use them when in battles with restored items between rounds.
There's a lot of other good Hold Items that are one-use items which are best used only in the tournaments where you can get them back (or in player vs. player matches, which do the same), like Air Balloons, Focus Sashes, Eject Buttons, Absorb Bulbs, and White Bulbs and other stuff that greatly benefit Pokémon in battles. (The shops at the tournament centers actually sell them, but you have to win a lot before you can gain enough credits to buy them, so its best to only use them in the tournaments themselves).
PP Ups (and PP Maxes, but these are just the equivalent of 3 PP Ups) permanently increase the total PP of a single move. In the several generations preceding Pokémon Black 2 and White 2, they cannot be bought anywhere, and only a handful exist in the field; if you're incredibly lucky or patient, you can collect more with the Pickup ability, but it's not really worth the effort to most people. Many players never use them, because even if you think you know exactly which move to boost, you might have to overwrite it later, making it a waste.
The items that fall under this are Water of Life (revives a party member, you'd normally have to reach a town and pay a fee), Psy Crystals (restore full PP instantly), Vials (+500 HP, most characters won't have this much until near the end of the game with a full complement of Djinn), Potions (Full HP) and Mist Potions (heal everyone for ~300 HP, only outclassed by Pure Wish, which you need a lot of level grinding to get). You only find so many of them, and once you use them, they're gone. (If you sell them instead, shops can sell them back to you as rarities at 1.33x the price.) They eventually become useless when you learn Revive (the main character of all games is a Venus Adept, who can learn it by setting 4 Djinn of the same element; other Adepts can learn it in nearly any class that requires 4 Venus Djinn), gain access to equipment that regenerates PP in battle, and gain backup party members that can safely spam healing spells between fights while recovering their PP by walking around.
Summons. They deal massive damage (especially to bosses), boost the summoner's elemental affinity temporarily, and some have added effects. To use them, though, they require that you unleash your Djinn, which prevents them from giving you a better class and (probably) important spells like Revive. Although they will recover (at a rate of one per person per turn, when you need four per person to do any real damage), the immediate effect makes such a tactic a Death or Glory Attack.
In Super Mario RPG there are tons of these. At the end of the game you have enough of these that you have to actually start chucking the "lesser" amazing items when your inventory fills up. Thankfully most of the really awesome items have either multiple uses or easily-acquired substitutes. The game, to its credit, does try to avert this by occasionally allowing "Freebies", which mean the item is not used up.
The best example is Kero-Kero Cola, a Megalixir-equivalent that can be bought en masse for an expensive but comparatively worthwhile 150/200 coins, depending on where you get them. By comparison, Max Mushrooms (which heal a party member to full HP) can only be bought at the Very Definitely Final Dungeon and Royal Syrup (which restores FP to full) can't be bought at all. Kero-Kero Cola does the same thing as both items combined, and on the whole party, too. Unless money is an issue (and given the genre, it probably isn't) you'll never be in a position where using the rare item is better than using a Cola.
One of the biggest items of them all would be the Red Essence, which leaves a character invincible for three turns and is very hard to find.
Flower Boxes, Jars and Tabs completely recover your FP alongside raising it, so you'll often save them for when you start running low so as to save your normal recovery items.
Another one is the Rock Candy, which deals 200 damage to every enemy in the battle. Too bad that the average player will only find about three throughout the entire game. Most players know exactly what they're saving all the Candies for: Culex.
Mario & Luigi: Superstar Saga has Golden Mushrooms; there are only about 4 you can ever get in hidden courses, and they fully restore the bros' HP and BP.
Jammin' Jelly, and to a lesser extent, the Ultra Shroom. The latter gives Mario 50 HP when used, while the former gives you 50 FP. Since you can only level Mario's HP and FP up to 50 (to have more than that, you need the HP Plus or FP Plus badges equipped), chances are you'll have one or two still in your inventory when you beat Bowser.
You can combine the two into a "Jelly Ultra" which restores both HP and FP by 50. Doing this may seem like a good idea, but doing so will cause an extreme mental block which will prevent you from ever using the item. Other high-end recipes can fall into this trope also. Further, the Triple Dip badge grants you the option of using three in one turn, giving you the option to restore 85 more HP and FP than Mario can possibly have, you know, when the time comes.
Paper Mario: Sticker Star has this far too much, as any and all combat relies on consumable items. You will find yourself hoarding Thing Stickers and Shinies and Flashies to the point where some players start actively avoiding battles just so they don't have to use up their items.
In the earlier Dragon Quest/Dragon Warrior games, you can pick a leaf from the World Tree which has the power to resurrect a dead party member without having to use a costly magic spell that has a chance of not working. However, you can only pick one of these at a time, and those that are hidden around the world were One-Time items. (A few of the games have them as Casino prizes, but that requires a lot of luck or Save Scumming.) Dragon Quest VIII permits you to buy or otherwise legitimately acquire two such leaves; however, it's possible to smuggle a third into the inventory via the game's item-crafting system.]
Dragon Quest IV boasts the World Dew, medicine derived from World Leaves that can heal your whole party. Again, you can only have one at a time; though it follows a "one at a time" rule quite similar to the game's Leaf of World Tree. Fortunately, despite the limited supply, both were free.
Dragon Quest VII also boasts the World Dew, but unlike World Leaves, you have to buy it from a shop that was always crowded, and wait your turn in line. And it's possible for them to "run out" before you even got to the counter...
The wisdom rings are too awesome to use as well as it's rare, one of the only ways to recover magic points, and breaks after several uses. Same with Elfin elixirs which recovers all MP. Some games have them offered as casino prizes.
Breath of Fire III has a pair of skills. Bonebreak is one of the game's strongest attack skills, and Celerity bestows godlike stat buffs. Both skills are usable at zero ability point cost. The catch? After using either skill, you have to wait five in-game hours for it to recharge. Considering that the game lasts about 30 hours and you get neither skill until very late in the game (and after tons of long, hard level grinding), it goes without saying that you'll probably never see either put to use until it's Final Boss Time—assuming you feel like expending the effort to acquire the skills in the first place!
The dragon form in Breath of Fire: Dragon Quarter is so powerful it can demolish any enemy with ease, even bosses. But using it increases your D-Ratio, which triggers a Nonstandard Game Over when it hits 100%, and there's no way to reduce it. And it still increases gradually even if you don't use your dragon powers.
In every game, Elixirs restore all of a character's HP and MP, and Megalixirs work as Elixirs on the entire party. Unless you plan to spend hours trying to steal more of them from specific enemies, you'll only find a small handful of Elixirs in any given game and probably one or two Megalixirs. In some of the games Ethers also cannot be purchased and so are also very valued unless you know where to steal them from, if you can steal from some of the enemies.
Shurikens, and most other throwing weapons in the original version, are powerful weapons capable of great damage, but are only available from an obscure shop just before the final dungeon. The ones you find before the shop opens will most likely still be in your inventory when you can finally buy them.
A greater example is the Spoon Dagger, renamed to just Dagger in some versions. Only one exists in the game and it requires going through an out-of-the-way optional dungeon twice to get it. It does an instant 9,999 damage to whatever you throw it at, so you're probably going to save it for the last boss.
The junction system essentially discouraged the player from using magic, since you'd either be saving up your best spells to junction with a specific stat or you'd have them junctioned already, meaning you were left with the lesser spells that weren't worth using on account of the stat boosts from the junctioned spells.
The Hero and Holy War items, which make respectively a single character or the whole party completely invincible for a short period of time. They have to be mugged off of certain bosses and are thus very limited in quantity... unless you go to the trouble of playing the card game. Winning the Laguna and Gilgamesh cards — a difficult task but not Nintendo Hard — and refining them with the Card Mod ability gets you 100 Heroes and 10 Holy Wars, more than enough to get you through all of the game's toughest boss fights.
The boss, GF, and character cards in Triple Triad are immensely powerful, but using them in a game risks the chance of losing them, and having to go through the hell of trying to get it back. Notably enough, if you grind the card game enough to unlock its secret quest, you can refine the cards and recover them an unlimited amount of times, essentially making the card game entirely a whole different level of Game Breaker.
Final Fantasy IX has the Dark Matter item. Unstoppable, unreduceable 9,999 damage for zero MP cost, and there are only three in the game. Smart players, on the other hand, will keep it around just long enough so their summoners can learn Odin off it, and then use it on a boss.
Any item that has an "Enchantment" effect with a limited number of uses is almost always Too Awesome to Use... Even when it's not. Items such as Trick Staves, Anniversary Rings and Raphael's Rod are rare in that you can only hold one and they're actually hard to obtain, so players will let them collect dust in storage unless they know they can get another. Items with unlimited uses but high timers (Tidal Talisman, Nexus Cape) are sometimes Too Awesome to Use because you almost always find yourself needing their enchantment when you've already used them and still have days remaining on your timer. Items with limited uses that are easy to re-obtain (such as Warp Cudgels, Reraise Earrings or Emperor Bands) subvert this trope, unless those items are being held for resale. Then they're Too Awesome to Use because a "used" Enchantment item cannot be sold on the Auction House.
Every job has an ability that, once used, cannot be used for another two hours. But many of these abilities never get used because players either want to hang on to them in case the party gets into a bad situation or the like, at which point it's probably too late anyway, or a waste — Benediction results in the user getting much too much aggro to avoid being the enemy's target, and Hundred Fists, which allow the Monk to hit repeatedly with almost no delay, usually can't do enough damage to kill the enemy before it starts offing players late in a battle, for example. One exception is Corsair's 2hour, Wild Card, which can recharge 2hours for others in the party... except other Wild Cards. If you're lucky, you can make quite a bit of money on the side by having your level 1 Corsair use Wild Card for random people who'll pay you for success.
The game has only four elixirs in the game. If you do dare to use them and do so intelligently though, one is usually enough to drop the scales in your favor.
Shrouds, which are field items that pre-buff your characters with every conceivable positive status or let you dodge enemies entirely. While they can be bought in shops, they're not available until almost the end of the game, and even then they're ridiculously expensive. On top of that, they almost never drop from enemies unless you either rank extremely low on a Random Encounter or have a certain accessory equipped. Needless to say, you'll want to save the 20 or so you get through the course of normal play for the endgame Bonus Bosses or the later Eidolon fights.
Elixirs take yet another step in usefulness and rarity: using one restores all of Lightning's HP and EP, fills all her ATB gauges and casts all otherwise rare buffs on her, all of above being even more significant than usual considering you start off being only able to carry 6 healing items in total and can increase it up a grand total of 10 on your first playthrough. The only ways to get one are to find and sell a total of 100 Soul Seeds (80 in New Game+) to the merchants that buy them or to find an Outerworld NPC that's selling one for the low, low price of 360,000 Gil, and doing either of above nets you an achievement or trophy.
Considering the relative difficulty in getting large amounts of EP on higher difficulty levels, even Ethers and Turbo Ethers count as this considering they're also only available as rewards from a select few sidequests or found from the Bonus Dungeon.
Megalixirs are more or less the same as in Final Fantasy, generally only available through costly synthesis, a few chests, or some other very time consuming method and serving the same purpose of completely restoring you and your party.
Kingdom Hearts: Chain of Memories: The Random Joker cards. Exceedingly rare, and one Random Joker fits any critera for opening a door. If you manage to get one, you'll probably end up saving it until you reach the Final Boss, just in case you find a door with an even more insane requirement.
SaGa / Final Fantasy Legend II naturally has these; almost every item has a durability counter. The ones you can't buy of course will fall into this. A lot of these can be found in the Nasty Dungeon. The Glass sword, which deals 1000+ damage ignoring all defense, breaks after one use. There is also the Hyper cannon, which will instantly win any non-boss battle, but it can only be used three times. You can equip the latter on a robot for one regenerating use, but the limited space on a robot itself is Too Awesome To Use. The DS version features even more of these.
The Key items in the Shadow Hearts games allow a character to extend a physical attack string according to their number, as long as the player can keep hitting a series of timed button presses.. The Third Key allows for three spins of the judgement ring, the Fifth five, and so on. The Eternal Key allows to extend a physical attack string infinitely. Get enough hits with one, and it'll kill literally any enemy in existence through overwhelmingly huge damage. Of course, there's only one in each game.
In Valkyrie Profile, there are two types of items that fall into this - Slayer weapons, and Great Magic staves. The first deal insane damage to certain types of enemies, but are breakable, and you'll never find one that isn't. Great Magic staves are stupidly powerful (the first one you'll find is in the triple digits for MAG when what your mage likely has barely breaks two digits), and naturally, unlock the specials for mages. They're also extremely breakable - some have a one in three chance of shattering. Unlisted are tricks for preserving these items (oneshot the enemy to keep the slayer, just don't use Great Magic to keep the stave), so newbies or inexperienced players let these sit.
People went through the game saving up on attack items like bottle rockets to use on the final boss, only to find out in the end that to beat him, you have to sing to him.
There is also a healing item called a Hand-Aid which recovers all your HP and PP, but there is only one of it in the game. Fortunately, EarthBound allowed you to buy the various types of bottle rockets (and for fairly reasonable prices considering how much damage they can do). So bottle rockets are no longer Too Awesome to Use.
Then there's the Bag of Dragonite, which turns one character into a dragon (although this just means an one-time powerful fire attack). If it weren't for the restrictive nature of the inventory in that game, they'd never be used at all.
Mother 3 repeatedly asks you not to do this, telling the player it's no use carrying around items you never use. At one point a woman asks if you're the kind of person who "stocks up on food and never eats it."
The Neverwinter Nights franchise has this. This is mostly the case with powerful or even ordinary potions and scrolls, especially if your character is not a magic build. A lot of mundane but tough fights could have been made easier if you'd just used that barkskin potion or whatnot, but you keep saving it for the boss fights.
A great example is found in one of the expansions to The Elder Scrolls III: Morrowind. In a stump are five Ebony Arrows Of Slaying that do 5,000 damage apiece. This is enough damage to drop The Imperfect (The Dragon in one of the expansions, and also a giant magic robot that the offical guide refers to as a monster to take down) twice over in one shot. But the odds of getting these arrows back is low, so you will almost always save them for a rainy day.
Potions and antidotes. You'll instantly start collecting various buff, health and antidote potions, but when an opportunity arises to actually use them, you'll find some way to avoid 'wasting' them until that special moment when you really need them. As time passes, this simply has the effect of rendering the items useless, as a formerly effective health potion that just restores one hundredth of your now leveled-up character's hitpoints is no longer as valuable. Then you drop the junk because it weighs you down. To make room for new junk.
The Daedric Lava Whiskey from the "Wizard's Tower" expansion: Only one bottle in the game, does a slight amount of damage and paralyzes you in exchange for then healing a massive amount of health and summoning a Dremora Lord, which is one of the most powerful summonable creatures in the game
The "Dragonborn" expansion to The Elder Scrolls V: Skyrim awards the player the ability to summon the spirit of Karstaag, an extremely powerful frost giant. The downside is that, unlike most powers, which can be used once per day, Karstaag can only be summoned three times ever.
High level arrows such as Ebony and Daedric greatly augment a bow's power, but are exceedingly rare. Arrows cannot be crafted in vanilla Skyrim either, hence many archer characters tend to keep them sitting in their inventories and use less powerful but more common arrow types like Elven, Orcish or Steel. Dawnguard rectifies this by allowing arrow crafting at any forge, and mods are available on PC which provide a similar service.
Parasite Eve 2 presents a conundrum. The only way to buy items is with the in-game currency known as BP, which you get for killing monsters. Monsters don't respawn. This leaves you with the decision of what guns and ammo to use. Sure you can buy awesome weapons like an M4 assault rifle, the shotgun, or a single shot grenade launcher, but ammo costs add up real quick. So if you burn through ammo, you won't have enough for armor and other upgrades. Thankfully the most basic ammo is free in ammo boxes in certain places that have an unlimited amount in them.
The Monument Chunk, a consumable which offered massive combat bonuses, but was available only once in the entire game. It almost always wound up in the trunk of the car until after the end of the game.
The three special Federation super-medkits which you found in the special encounter with the crashed Star Trek shuttle. They restored your health completely, no matter how hurt you were - but there were only three in the entire game. As a result they inevitably ended up in a chest or other container, from which they would only be taken when really needed. Or not.
The Experimental MIRV: a modified Fat Man that fires 8 mini-nukes at once. Unlocking its bunker requires you to find five holotapes hidden at various places in the Wasteland. The average player probably won't find enough mini-nukes over the course of the entire game to fire this baby more than two or three times. No fight in the game justifies the use of such firepower, so the weapon will most likely remain unused. Great for showing off, though.
The Fat Man itself is an example, as there are very few battles that justify or require its use (other than some of the Super Mutant Behemoths, or the multiple Feral Ghoul Reavers in the Presidential Metro).
The Alien Blaster will disintegrate any target with a headshot, but there are less than two hundred rounds of ammunition for it in the entire core game. It's also the only one of its kind, unless you find the second one in the Mobile Base Crawler near the end of Broken Steel, and can only be fully repaired with Alien Epoxy.
You could also classify the Firelance under the same banner as the Alien Blaster. Only obtainable in a randomly found event (of which you may not even notice and end up walking away from). It's a unique variant of the Alien Blaster that sets things on fire as well as having a pretty punch. Because of the fire effect, it gets an extra 50% damage from the Pyromaniac perk. Add the Xenotech perk from the Mothership Zeta Downloadable Content to add a further 20% damage to it, and you can easily drop the toughest enemies with a decent Energy Weapons skill. Sounds good and all, but the event only spawns it with 12 rounds, randomly thrown about the nearby area, so you're not likely to find even half of them. The total available ammo for it in the game is around 280: 120 from the crashed Alien ship, 12 from the Firelance event itself, and ~100-150 from Fort Independence assuming you have the Scavenger perk.
Mothership Zeta and Broken Steel also include additional ammo for the Blaster. The other alien weapons also suffer from this, since there is a finite number of power modules.
With "Operation Anchorage", there is exactly one Gauss Rifle, and without Alien Epoxy from "Mothership Zeta", there's no way to fully repair it. Even though you could practically be swimming in its ammo late in the game, there's a hard limit on the number of shots you can fire (unless you abuse a glitch to get a nearly indestructible version from the computer simulation out into the "reality" of the Capital Wasteland).
Although it has the highest damage resistance of any armor, there is only one standard T-51b Power Armor, so it can only be partially repaired, and is best used for companion characters, where it won't degrade. Conversely, the Winterized T-51b is practically indestructible, since the main game version has the same astronomical HP as the Anchorage Simulation version.
The Fat Man again. Just as it and its ammo were impractically rare in FO3, the same applies here but in even more heartbreaking fashion. There are only 14 Mini Nukes (down to 12 if you have Wild Wasteland trait) in the entire game!
However, if you have the Gun Runners' Arsenal DLC, the unique version Esther along with its special ammo appear in the Vendortron's inventory at the Gun Runners kiosk. Among them are Mini Nukes that separate into multiple Nukes, which will fondly remind players of the Experimental MIRV. Not only that, but the special variants of the Mini Nuke can be purchased again after a couple of days have passed. They may be tremendously expensive, but you'll eventually manage it and then enjoy your fireworks. This makes Esther an Infinity+1 Sword.
Holy Frag Grenades. Their damage and blast radius is similar to Mini Nukes, but there are only three of them so use them sparingly. Oh, you also need Wild Wasteland trait, meaning you have to choose between them and two of the mini nukes. Although the grenades are a heck of a lot lighter than the Mini Nukes and do not require a launcher to use, the throwing range is much shorter, especially if you have the Loose Cannon trait. A bad throw can see you blowing yourself up.
The Alien Blaster qualifies even more, as it requires Wild Wasteland trait to even get, and has been nerfed from its Fallout 3 counterpart.
The unique grenade machine gun Mercy. It uses 40mm grenades rather than the normal 25mm ones for the grenade machine gun. However these bulky rounds were priced, distributed, and weighted with single shot use in mind, so Mercy expends through ammo value and weight faster than anything else. It is actually pretty useful to use at Hoover Dam at the end of the game, but otherwise its overkill.
Similar to FO 3's T51-B, the Remnants Power Armor, although having the highest Damage Threshold in the game, also is one of the rarest armors, has the highest rate of degradation, and is one of the most expensive to repair. Best reserved for the final battle. At least this time around there's a perk that allows you to use other power armor to repair it, but even then such armor is rare.
The physiological reevaluation done by the auto-doc in Old World Blues. Even though it could allow you to milk traits and swap them when not needed, you can only do it once.
Wild Arms had the extremely useful "Ambrosia" potion that revives, fully heals health and magic points and removes all status changes for the entire party.
The Bard's Tale has Adder Stones, which allow you to heal instantly, restrain enemies, become immortal for a brief period of time, and do several other cool things. This can result in completely unnecessary hoarding in case they need to become immortal later — people have died sitting on a decent collection of adder stones and entered the final boss fight with 102 stones (one is needed to heal, and 3 for immortality).
Baldur's Gate: Various awesome potions and protections scrolls just pile up in your inventory until the endgame, when you don't really need them since your mages and clerics can cast far mightier buffs on you. However, Protection from Magic and Protection from Undead scrolls MAY prove useful in the final levels. And for all that's holy, do hold like glue onto that Cloudkill scroll you find in the Firewine Ruins! Party mage + Cloudkill = the Big Bad's henchmen gone before they even see you.
Ultima frequently features the Glass Sword, which is very much one of these, killing any enemy instantly but breaking after use.
The Aura Of Valor maxes your Spirit pool allowing you to unleash your biggest attacks but you only ever get 2 or 3. The bright side is that the storyline bosses are easy to beat using the Game Breaker Justice/Delta Shield combo; you generally won't need to use the Aura unless you take on some of the sidequests. The downside is that trying to beat some of the Wanted battles (especially Daikokuya, the Ixa'Ness, and the Impostors) without using one tends to wander towards the hard side of impossible, and even when you do use it there's a non-zero chance they can recover from it (especially if you were fool enough to use Blue Rogues rather than Prophecy or Pirate's Wrath) and even in the best-case you'll blow a hell of a lot of Riselem Crystals to win the fight.
There's also the Tropica, a fruit that gives any character a 200 HP boost. There are only two in the entire game, and one of them is very, VERY easy to miss.
The All-Divide in Tales of Symphonia halves damage that the party receives and inflicts, and while it makes battles take longer, it makes it considerably easier to withstand enemies' attacks long enough to heal. Unfortunately, given how rare they are, most players will save them for That One Boss or not use them at all. The Playstation 2 version makes it worse since All-Divides don't work on That One Boss anymore.
Lampshaded in Tales of Vesperia when you discover an hourglass, a very rare item that stops time for a few seconds, a skit triggers where the party discusses using the item, with Raven firmly being this trope. Ironically, Raven can use a spell that replicates the hourglass, though getting that spell is a big Guide Dang It that can be Lost Forever.
Arcanum: Of Steamworks & Magick Obscura features Fate Points. Put simply, they provide a guaranteed critical success to the next use of whatever specific skill you chose (pickpocket, spell, attack, etc.) or instantly refill a meter of some sort (like health). They are extremely rare (about 25 technically), only rewarded for completing specific tasks, and are sometimes rewarded for different results in the same task (in other words, impossible to collect all of them). Good luck choosing those few very special occasions to spend them on. Most players would probably default to using them to gank powerful items that could otherwise never be stolen without being caught, but even then there are more such items than you have points to spend.
Somas fully heal a character's HP and SP, but they're painfully rare and just begging to be stockpiled. There's only ONE that doesn't require finding Mystical Chests, the contents of which will actually change if you open them in the wrong phase. How do you get it? Through a very-easily missed vending machine that stops working after the Conception. In other words, it's only available to you for the first 15 minutes of the game. Missed it? Too bad. Not to mention it doesn't actually say it's a Soma when you get it, until after the Conception.
This is inverted with HP healing items. Your average healing items are available on shops, but they are expensive up until mid-game and you're better leaving those to tough battles. To help with this, there are Muscle Drinks and variants and Life Stones: the first one heals a huge deal of HP but can cause one of the Standard Status Effects on use - being a Nintendo Hard game, you do not want to get afflicted with these on boss fights. The other one always heal a fixed low percentage, so it's never enough in mid-battle and you're better using them on the map. While fairly common, those are only available as Random Drops, and demons like to use them as bargaining chips if you're trying to recruit one mid-battle.
Incenses and Sacrifices. The first permanently raise one of your stats and fully heal your HP and MP, the second automatically revive and fully heal your main character when he takes an Expel or Curse instant kill attack, which would otherwise mean a Game Over. You only get a limited number of them, most of the times from completing determinate sidequests in a specific way, or finding very rare chests in areas swarming with high-level enemies. And you keep the Incenses between runs, while your stats reset, meaning a savvy player will stock up dozens of them to face the Bonus Bosses or Boss Rush.
Mirrors, who deflect all physical or magical attack on your whole party for a single turn, and have top turn priority just like other items.
Magic Stones aren't limited, but are annoyingly difficult to acquire, as each type of them needs certain materials to be gathered around or stolen from demons (and some can only be obtained through negotiation from certain demons - good luck getting anything at all from a demon of your opposite alignment!) and then processed back at your ship, while spending hefty sums of Macca in the process. And they're the only way a MA-Type Demonica can take full advantage of its stats, since guns that give access to similar skills are not only even harder to come by or alignment-locked, but those skill's damage is based on ST.
The "Soma" item returns, this time restoring the whole party's life and magic points. However there are only several in each game and they can't be bought from any store.
In the Updated Re-release "Persona 3 Portable", combination attacks now come in card form, purchasable from the antique store. Remember that Game Breaker, Armageddon? It now cost 99 Malachite and 10 Opal. Don't worry, you'll have that many if you saved for 80 levels.
In Persona 4, MP restoration items can fall under this. The reason being that, unlike in Persona 3, you can't buy anything that restores MP, only farm them from chests in dungeons. Considering that the general consensus is that you can only have a single, really long dungeon run each month (for the most part) if you want maximum efficiency in Persona 4, you kind of get the idea.
Geneforge: The Jeweled Wand, which lets you use the extremely powerful "Diamond Spray" attack that you can't cast on your own; it hits up to FIVE enemies for quite a bit of damage. The item is extremely rare, as well, with most players probably only getting one. Players usually save the item for the battle with Trajkov, Goettsch, or the Bonus Dungeon.
In Albion, you're a brave space-pilot, stranded on a medieval-level world with your scientist friend. Favored weapons amongst the natives includes swords, spears and the like. In the wreck of your spaceship, you find a gun and a handful of bullets for it - and, needless to say, you're not likely to find extra ammo anywhere on the planet. Hence, you'll probably never use it at all, even as the game's progression gradually gives you access to to powerful magic-users and enchanted weapons that can equal and surpass the handgun's power - and towards the very end of the game, you actually DO find plentiful extra ammo, and more powerful guns as well. Shame you didn't use the gun back near the beginning, where it would've actually been really useful...
In the Dungeons & Dragons CRPG Ravenloft: Strahd's Possession, the heroes can find a handful of Arrows of Slaying Undead very early in the game. There are only a handful available in the game. Good luck deciding when to use them.
In the Monster Hunter games, there are Max Potions and Ancient Potions: you can only hold 2 and 1 at a time, respectively. Max potions will heal you to full and increase your max total health to its maximum; Ancient Potions will do that and do the same to your stamina (though stamina recovers megafast anyway, but the max deteriorates over time). Max potions can be crafted, and with farmable materials, but they're a hassle... and Ancient Potions also require Kelbi Horns to make, which can be tough to get. And inventory slots are valuable. So, pretty much never gets used. They do have a good use for when you get killed, as that resets your max stamina/health and they're the only ones who can increase max health during a quest... but then you're wasting the healing component, and most don't assume they'll get killed during a quest/plan around it.
In Hydlide, the Medicine will revive you to full health when you die, but only once. Saving it for the Final Boss is pretty much obligatory.
Dark Souls has the not-that-common Ring of Sacrifice and the Rare Ring of Sacrifice, which prevent you from losing souls and humanity upon death, and the latter breaking the otherwise hard to remove Curse ailment...and break upon use. And then there's the Ring of Favor and Protection, which gives a boost to health, stamina, and carrying capacity, with only two(and one of them well-hidden) in the game, and they break upon being removed. And then there's the Divine Blessing: A very large heal that cures any ailment except curse, and of which only a limited number exist in each playthrough. In the DLC there is the Elizabeth's Mushroom, which provides a unique and very useful health regeneration effect. Those who use a Divine Blessing or Elizabeth's Mushroom in multiplayer will often be accused of being a hacker because of this trope.
In Mass Effect 2, the M-920 Cain is essentially a railgun with the power of a nuclear warhead (to the point of causing mushroom clouds and bearing the radiation hazard symbol) that does enough damage to instantly cheese some tough events. Unfortunately, it requires all of your heavy weapon ammo to fire once (unless you have the heavy ammo upgrades, then you might be able to fire it twice), has a four second charge time, is impractical in the many close-quarters firefights which populate the game because of its blast radius, and fires a relatively slow projectile. The last boss is one of the fights you'd want to use it on, but he flails around like he's having a seizure, making hitting him an exercise in frustration, so you might save it until the end... and then completely blow it.
The game Fullmetal Alchemist and the Broken Angel has a system where you can turn things into weapons using alchemy; you can make the basic weapon and a more advanced one, and can add on elemental bonuses to them. You can, for example, create a broadsword and attach fire to that, which is pretty powerful, or you can make the more advanced weapon, a katana, but it comes at a cost; you can't attach an element to it, and, while it is powerful enough to take out an enemy in a single hit, it is used up after about six hits, leaving you running around wildly looking for something else you can turn into a weapon.
Class skills in AdventureQuest generally fall under this trope, especially with the newer/revamped classes introduced after Skill Points were released. Class-based attacks and defensive skills are some of the best in the game, but nearly all of them come with prohibitively high SP costs. Class-based attacks are also prone to missing just as often as regular attacks, so using them will basically amount to wasting a boatload of SP, even if it actually does something. Okay, so what about the unchanged classes introduced before SP came along? They tend to act as a Mana sink instead; conserving Mana is very important, since you will probably need to cast a healing spell at least once a fight regardless of what armor you decide to equip.
The Dark Chips from Mega Man Battle Network 5, which can be considered the most powerful Chips in the game but each time you use on, Mega Man's maximum health is permanently decreased by 1. Some players absolutely refuse to use them for this reason even though they can at times be GameBreakers.
Opoona has the Popcorn Shower item. It can only be bought from the OMP Point Shop for 1000 points, the equivalent of 100,000 Matia. It does almost 1000 damage to every enemy in a battle... but even the game's burliest random encounters only have around 400 HP, so few fights require that kind of firepower. There are a few where it would be worthwhile (such as against the Boss in Mook Clothing enemies), but in areas where they appear, they aren't as uncommon, leaving players to wonder if they're really in a bad enough place to use it.
Radiant Historia has a few, ranging from valuable but reasonably obtainable to absurdly rare:
Celestial Dew restores 200 MP to the party, and there are only 2 of them in the game. The Celestial Tea and Celestial Oil (full-party 50 and 100 MP restoration respectively) are a subversion, as while they are equally hard to find and cannot be bought in shops, they can be stolen from a few late-game enemies. Radiant Historia's stealing mechanic tends to have a fairly high success rate and the enemies can be respawned, so it is not too hard to maximize your stock of these. The same goes for Healing Fruit, Superior Tea, and Divine Water (full-party 300 HP restoration, single-person 150 MP restoration, and single-person revival and 500 HP restoration), which are valuable but can be purchased late in the game.
The Medibranch, which has about the same rarity as the above and restores 1000 HP to the party (most characters, by the way, will not have that much HP even at level 99).
To a lesser extent, the Shield Seeds, which can block attacks and are also unavailable in shops.
Finally, Mana Crystals can only be used at save points but will fully restore the party's HP and MP, and aside from the three you get for free at the beginning of the game, they are hard to find and relatively expensive to buy. Players might want to save them for late in the game when the restoration will be of a greater magnitude (since, naturally, the player characters will be at higher levels and have greater maximum HP and MP values).
Eternal Sonata has the Saint's Mirror item, which revives anyone that is KOed and restores them to full HP. However, there was only to be found normally as treasure in the main gameplay. Another was available as a drop from a boss fought only in Encore Mode. While there was a regular enemy that dropped them in the Bonus Dungeon, Mysterious Unison, it was an extremely rare drop. Further complicating things in the original Xbox360 version was that they carried an item weight of 10. The PlayStation 3 version changed this to 2, making their inclusion in your inventory at least more practical.
In nearly any game where Magic Is Rare; Health Is Cheap applies, the MP-restoring items will fall under this trope. Depending on how cautious and conservative a player you are, even the MP itself could qualify if you're not near an inn or other place where it can be easily replenished.
Bombs are very useful in Star Fox, and are instrumental in a few boss fights. You don't find yourself using them too often, though, do you? Doubly so because killing multiple enemies with a single Bomb does not offer the same cluster-kill bonus that doing the same with a charge shot does. It mostly comes down to a matter of only using it on enemies that you KNOW you can't clear out anyway, and memorizing the points where more bombs appear so you can be sure a replacement is right around the corner.
In Thunder Force III onwards, dying takes away your current weapon unless it's Twin Shot or Back Shot, your initial weapons. Less experienced players who are aware of this penalty may find themselves refusing to use the better weapons, out of fear of losing them.
Splinter Cell: If you didn't realize you could use the Sticky-Cam to knock out people, you'd end up hoarding Sticky-Shockers and Airfoils right past the point where they'd be useful. (And the games would often have Sam inexplicably dump several of his items during loading screens, rendering all your hoarding moot.) Conviction rectifies this by giving players "Weapon Stashes" that top off all the player's ammo whenever they're used.
Nearly all entries in the series have players finding themselves with dozens of magazines worth of ammunition for their weapons, and their larger guns all but unused by the time they meet the final enemy, which most likely cannot be hurt by any of those weapons, even the big-ticket firearms. Sometimes, though, they're nice enough to make it fairly obvious what you're saving them up for by making every other option you have practical suicide (e.g. by the fifth time in a row you've been decapitated by a Hunter or tentacle'd to death by Nemesis, it's pretty clear you can go ahead and start using that nice, shiny magnum now).
Ink Ribbons. While most typewriters have at least one and possibly as many as three ribbons nearby, the prospect of running out and being unable to save is quite scary for many players.
In Resident Evil: Code: Veronica, the SMG's and the assault rifle are too awesome. The Magnum you'll definitely need for the later bosses, and if you left the Fire Extinguisher (which you need to extinguish the fire blocking the path to it) behind in the security box, it'll be Lost Forever. Best part? There are only eighteen extra rounds for it in the whole game.
Resident Evil 4 has this with the rocket launcher, which is very powerful (can one-hit just about every boss in the game), but is still better to sell for cash and use that to upgrade one of your guns that gets more than one use.
Resident Evil 5 ends up playing this trope semi-straight (or at least straighter than the previous game did) due to its more limited inventory system. With only nine slots available per character, space is at a premium and it's usually best to rely on the weapon you have the most ammo for, if only to keep your inventory from being clogged with four or five superfluous ammo boxes. Sadly, the ammunition for the best weapons in the game (magnums and the grenade launcher) are almost impossible to find. And even when you do find magnum and grenade rounds chances are you won't have either of those weapons in your inventory since you so prudently chose to store them away in your hammerspace inventory accessible only in between chapters. However, while there's nothing to be done about the inventory space, the game also doesn't think to take away items you picked up if you quit a chapter, so you once you find them you can stockpile magnum ammo, grenade rounds, and even rocket launchers with relative ease.
The more powerful weapons, such as the Rifle in the first two games and the Submachine Gun in the third, tend to have the scarcest ammo and should be saved for major boss fights. The Ampoule, an item that heals all of your health no matter how badly hurt you were, also suffers from the same scarcity and often ends up never used at all.
The game features unkillable Victim ghosts that haunt the player throughout the entire game. Your best defense are the Swords of Obedience (there's only five of them) and the even rarer Silver Bullets (there's only three, the last of which is a Bragging Rights Reward). Swords will pin down a fallen Victim for the remainder of the game; Silver Bullets will instantly "down" a Victim. Usually, players save the Swords for pinning down the four toughest Victims Cynthia, Jasper, Andrew and Richard, while hogging the Silver Bullets for the latter two, essentially bypassing two of the hardest fights in the game.
Holy Candles and Saint Medallions. Both are effective means of defense against Victims, and come pretty early in the game, but players may choose to start saving them for the second half of the game, when the apartment starts suffering Hauntings whose exorcism directly influences the ending of the game.
In the Lovecraft-inspired Mystery-Survivalhorror game Eternal Darkness, you will, except for the first chapter, never use healing items since they have only a limited amount of uses and you will often very early find the Tome of Eternal Darkness, which lets you cast Healing Spells among others and your Mana recharges. The same can be said about your Guns and other weapons that require ammo, because the moment you find a melee weapon you wont use your guns on normal zombies any more and only save them for the arcane horrors and Gurdians. Or not even on them, but you will save them for the really big Eldritch Abominations at the end of the chapter, only to find that they are immune to bullets. Also, the chapters often end very abruptly, and your items do not get transferred to the present, so you will probably fight yourself through the chapter only with melee weapons and spells to save your ammo, and then see it all gone due to the chapter ending.
Deadly Premonition has Thomas' Biscuit. You're only ever given two in the game; they refill all of your hunger and tiredness, as well as your health and stamina, and keep them low for longer. The first one given to you by the game is shortly before the final boss fight, meaning most players will probably use it there, but the other one comes during a Boss Rush with ample opportunities for saving between, meaning the second biscuit is likely to sit around in player's inventories all through the Playable Epilogue.
The Smart Bomb in Alien Swarm. When you unlock it, you can carry only one. It's pretty much the same as the Hornet Barrage, but 5 of them. It fires so many damn rockets that a huge swarm can easily be dispatched with the item. However, since you can only hold 1, you'll have a tough time figuring out when is the best time to use it.
Most emergency plants, i.e. Cherry Bomb, Jalapeno, Doom Shroom, etc. Most of them get pretty expensive at 100 sun upward for an explosion, when you could be spending your sun on permanent attacking plants. They also take forever to recharge, so you can't use one back-to-back for multiple emergencies.
Most of the plant upgrades qualify in anything that isn't Survival Mode. By the time you have enough sun to turn all your Sunflowers into Twins or your Repeaters into Gatling Peas, the round is most likely over already. In the case of the former, as well, it costs so much sun to upgrade to Twins that the Sunflower has to pelt out sun 6 times before you start making profit off of it.
The unique S-rank staves in various games (e.g. the Ashera Staff in Path of Radiance). They heal all your allies on the battlefield as well as removing all status ailments and give enough experience to the caster for a level up. But they only have three uses, and in order to use them at all you need an S-rank in staves (which has no other purpose and, in some games, stops you from S-ranking any other weapon type). This at least is not so much a problem in Radiant Dawn, because you only get the Ashera Staff from a character (whose method of recruitment approaches a Guide Dang It) that joins in the last chapter, and it can be freely used in the fight with the Big Bad.
And in a similar case, the Hammerne staff, which can repair almost any item in the game. Again, three uses before it's gone forever. However, the Hammerne staff can be used to repair other Too Awesome To Use items and weapons.
Most of the long-range magic items suffer from this trope. They're quite powerful and can be used from very far away, but are not common and have only 5 uses. In Radiant Dawn, if you have them blessed near the end of the game, they become infinitely usable making them partial Game Breakers.
The majority of S ranked, Brave, and special weaponstend to fall under this trope. For example, the Vague Katti is a decently powerful sword, but its true strength lies in its 35% increased chance of landing a Critical Hit. Too bad it only has enough uses to be good for one or two chapters.
Blazing Swordreferences this when a character warns not to put too much thought into who gets an item; 'holding onto a useful item does no one any good'. However, said NPC appears in Lyn's mode, and saving the item will help up your funds ranking. A higher funds ranking means Lyn has a better gem in her inventory in Eliwood/Hector mode, so ironically, this is the one time not using an item IS helpful (though it's debatable whether the better funds ranking and the extra gold later on outweigh the stat bonus from using the item right away).
Sword of Seals actually forces this behavior. You have access to the game's ultimate weapons very early, but they have few uses, and in order to get the best ending they all need to be intact by the time you beat the Big Bad. Even though you technically CAN use them 1/3 of the way through the game, not players won't until the very end.
Going for an overall A Funds ranking also enforces this kind of behavior, as it's based on the total monetary worth of all items in your posession. Expect the wast majority of Silver weapons to get hoarded in the convoy and never used. Also note many forum members consider this the only way to play.
Myrrh from The Sacred Stones is an example of a character that is too awesome to use. She is a cute person that also happens to be an extremely powerful dragon, but she required her Dragonstone to attack. Every attack, even counterattacks, costs one charge. The problem is that it only has fifty charges, there's no way to repair it (outside of a Good Bad Bug) and the one in her possession is the only Dragonstone in the game. Use it up and Myrrh will become completely useless. (The trick is to learn when to start using her so her level is high enough to be useful—yes, part of those 50 charges must be used for leveling her up—and yet leave the Dragonstone with enough charges to maul the True Final Boss.)
Sid Meier’s Alpha Centauri's expansion pack introduced Battle Ogres. These are alien war machines left on Planet that really kick ass, especially the Mark 3. Problem? They are rare, and damage to them can never be repaired. So despite having very good weapons for when you pick them up, they tend to sit around as garrison units, because they have an ability that makes them better police. They're also good stopgaps in the case of mindworm swarms, as they have not only good defense but (in the mark 1 and 2 versions) additional defenses against psi attacks. Just be sure to never let them get into real combat.
In most normal gameplay, you won't need to use the Jonathan Ingram card in Metal Gear Ac!d, despite it being one of the most powerful ones in the game. Ingram removes twenty COST from your character, far beyond the twelve COST removed by the most powerful conventional COST reduction card - but, because Jonathan Ingram is so powerful, it tends not to get used.
The three one-shot ultra-weapons in Odium (a missile, a lightning and an energy beam). They cause colossal damage in a huge radius.
The Samurai class in Final Fantasy Tactics has the ability to unleash area attacks from the different katanas available in the game. However, using them in this fashion had a chance of breaking them. While some of the weaker katanas were easily purchased (including, fortunately, one that restored allies' health), the most powerful ones were available only as rewards in battle (or via stealing from enemies). While you could just equip said katanas and use them for melee attacks to your heart's content, the special attack (which could break the katana) wound up never used.
See that beautiful Allmighty Antilaw in Final Fantasy Tactics Advance? It allows you to completely nullify all laws in the battle. Which means that they are the ultimate anti-judge weapon. But then it should be noted that it is limited to very certain plot points of the game. This extends to a lesser extent to the R level law cards which are still rare, but they can keep returning to the card shop. But good luck on getting yourself to use them too because often times you will just stomach the laws to begin with.
L.A. Noire has Intuition Points that allow you to find all clues and ease questioning, you also only get a limited amount of them and can only have 5 at once. This is inverted after you have completed the story, which lets you go back to any previous case and always start with 5 Intuition Points. This encourages using them to achieve a perfect rank on that case.
In most games, getting a vehicle you want to keep generally means it will stay in the garage forever, since if you take it to do a mission, you will likely have to get out of it and risk it disappearing, and they are ridiculously easy to destroy.
This is taken to insane lengths in Grand Theft Auto III. Certain plot-involved cars are immune to certain things, such as bullets, fire, explosions, and wrecks. Most of these cars could only be obtained ONCE per game and often required hours of trial and error to get. Many players spent many hours collecting them, just to have them waste away in a garage, even though some missions almost require one to complete.
Another notable mention of this trope are the combine harvesters in Grand Theft Auto: San Andreas. These vehicles had the unique and delightfully sadistic feature of turning crops of pedestrians into neatly bundled up bales of body parts. Unfortunately, the harvesters are rare, encountered only at certain times in rural areas. In addition, almost all of them are locked and can only be accessed by killing the driver of one already in use. Even after obtaining one, the size of the vehicle makes it difficult to move in populated areas and impossible to fit into a garage for safe keeping. Its slow speed and bad handling make the player easy for law enforcers (who inevitably start to show up after a few good mauls) to catch. Finally, if the player decides to exit the vehicle for any reason, the door locks behind them.
No More Heroes has Anarchy in the Galaxy, the most devastating Limit Break move in the game that clears the entire screen of enemies. It's also the onlyLimit Break that can not only be triggered at will, but stacks as well in case you get more than one over the course of a level, and you get a sizeable cash bonus if you make it through the level without using it. The cash bonus increases on subsequent playthroughs. It also does squat to bosses.
Golden apples, the only food that gives the largest amount of hunger restored (5 units) and grants 30 seconds of regenerating health, regardless of hunger level. Red apples alone are incredibly rare, only being found occasionally in dungeons, or dropping off Notch, the game developer, should he grace your server. To make a golden apple, you have to encase that red apple in 8 cubes of gold. A cube of gold takes 9 gold ingots. You would have to mine and smelt 72 blocks of gold ore, a fairly rare material found underground or dropped in nugget form (1/9th of an ingot) by Zombie Pigmen, in order to have enough material to make a single golden apple. Before the 1.8 update, the Golden Apple was more of a status symbol than anything since other food at that time was more plentiful and healed a good amount of health. Golden Apples can be found in dungeons, but you only have a 1 in 125 chance of actually getting one.
Some consider diamond equipment to be this. A pick-axe made of diamond mines faster and lasts a lot longer than one made of iron or stone... but it still breaks eventually, and if you're killed by underground monsters or a lava flow, you risk losing it forever. Similarly, diamond armor offers a great deal of protection, and diamond swords deal 25% more damage than iron swords, but since they're only useful in combat, there's a serious risk of losing them long before their unparalleled durability runs out, especially when diamond armor provides not much more protection than iron, which is plentiful. Diamond is found deep within the earth, usually near lava, and is even rarer than gold. It can still be worth using with proper branch mining techniques, but it is time-consuming to hunt for.
Ender Pearls. Endermen drop them when killed but they are difficult to kill quickly due to their Teleport Spam and the drop rate of the pearl is low. Throwing a pearl will teleport the player wherever it lands (but hurt you when used to prevent people from spamming the pearls nilly willy), making them excellent tools to climb hills or to cross large gaps, but since the pearls are not common, players will either store them up and never use them or wait for the worst possible scenario to happen before using them. On top of that, an ender pearl can be combined with blaze powder to create an Eye of Ender, and you'll need up to a dozen every time you want to activate a stronghold portal to The End, not counting however many you use up trying to locate the stronghold.
Enchanted tools and armor. You can get some nifty effects for your items, such as setting mobs on fire or increasing the diamond drop rate. However, the enchantments you receive are pretty unpredictable, and the experience cost increases quadratically with the enchantment level. You'd have to kill 77 hostile mobs for level 10, 651 hostile mobs for level 30, or 1785 hostile mobs for the maximum, level 50. Furthermore, enchanted items can't be repaired without stripping the enchantment. They basically have all the drawbacks of diamond equipment taken Up to Eleven.
Potions are risky to use at most. Health and regeneration potions are handy to have since they can directly restore your health regardless of your hunger level, swift potions boosts your speed, strength potions gives your damage a boost, and fire resistance potions makes you immune to fire and lava. However, most of the ingredients needed are difficult to find and the majority of them are found in the Nether where the most difficult monsters are found and hold drops needed to craft the potions. Once you actually get the ingredients and craft the potions, you may be tempted to not use them at all in fear of wasting their effects if you get killed.
Depending on your playing style, the blunderbuss from Red Dead Redemption: Undead Nightmare may qualify. Hands-down the most powerful gun in the game, it blasts zombies into a fine pink mist with one shot (several of them if they happen to be in a tight cluster). The ammo is made from dead zombie parts (ribs, eyes, ears, and tongues according to the RDR Wiki) and it takes ten zombie parts to make one unit of blunderbuss ammo. However, if you blast the undead apart with the blunderbuss you can't loot their bodies for ammo ingredients, which forces you to kill zombies normally. If you can kill 10+ zombies with conventional weapons you probably don't need the blunderbuss anyway.
Terraria has the Star Cannon. Shot for shot, it's the most powerful weapon in the game, and it can be crafted fairly early. The catch is that it uses Fallen Stars as ammo. Fallen Stars are dropped at a very low rate at night (you'll get maybe ten or twelve if you scour the earth), are used in many other crafting recipes (including the essential Mana Crystals), and can't be reused once fired. Furthermore, the Star Cannon has a ludicrously high rate of fire, so even with armor that reduces your ammo consumption, you'll end up burning through your star stockpile at a fairly quick speed.
Mercenaries: World In Flames has this issue with its various Airstrikes/Supply drops. If you had a strike available you need only aim at the target area, and call down the thunder/goods. They can even be found at a decent frequency. But you are constantly in paranoia that your large mortar strike won't be as useful here clearing out a random enemy outpost, as it would there... the next enemy outpost. There's only one instance where an airstrike is necessary, and you use a nuclear bunker buster for that one. Aside from that, players are likely to have enough large munitions stocked up to support a small army.
Some cards in Magic: The Gathering are specifically designed to invoke this trope, by giving you a small cheap effect and/or a large expensive effect. Good players will know when getting it out now is more important than making it more powerful; bad players will not.
One such example is Kavu Titan; when they were playtesting Invasion and someone lent now-head Designer Mark Rosewater a deck to use without mentioning that the Grizzly Bears (a basic 2-mana card with two power/toughness, similar to Kavu Titan without its kicker) were supposed to be proxies for Kavu Titans. Mark went 4-0 the first week, and then upon being told that they were actually Titans, he went 2-2 the next week, wanting to hold back to use the Titan's improved version rather than just pouring on the aggression.
Another example is the Chaos Orb, a card which is tossed from a specified height onto the gaming table and destroys any card it ends up touching. It is now banned entirely from tournament play, but in the early days a story went around about some players came up with the clever idea of tearing up the Chaos Orb card and scattering all the pieces across the opponent's side of the table. This was eventually deemed illegal, but anyone with the cojones to pull a stunt like that with an extremely valuable out-of-print rare deserves to get the win.
There are also the Planeswalkers, which often have a small ability that keeps them alive, and more powerful abilities that can often kill them or leave them near-death, and they can use only one per turn. Garruk Wildspeaker, in particular, gets this treatment: "Do I untap two lands or Overrun?" is a legitimate question.
The Wish spell (starting from Basic D&D), and its divine counterpart Miracle (much later) can do almost anything. In a normal campaign, however high-level, no-one will ever cast them, unless suicidally desperate. The cost and having to deal with possible twists simply aren't worth it. First edition encourages the DM to be as much of a jerkass literal genie as the wish wording allowed. Second and third edition restored some balance by adding "safe" uses of the spells, making them quite useful. For example, they can be used to imitate any other spell below certain levels, even granting access to spells that the character would otherwise never be able to cast.
Spellcasters are limited by the number of spells they can cast throughout the day. Some players tend to underuse their high level spells, holding back just in case they get into another combat before they can recharge.
Magic items, including scrolls, potions and items with charges, are often underused by most players, particularly in campaigns that where magic items are particularly rare.
4th edition attempted to avert this trope:
Encounter powers are usable once per encounter, so it is a waste NOT to use them, as if they go unused you gain no benefit at all. Action points (which give you an extra action, though some characters can gain other uses for them) are restricted to being used once per encounter, you gain one every second encounter, and they reset after the adventure, encouraging players to use the resource. Sadly, many newbie players don't understand this and play this trope straight until it is explained to them; the optimal strategy tends to be to use all of your encounter powers straightaway, and to either use an action point in the encounter immediately prior to gaining another one (so the 2nd, 4th, ect.), as well against any sort of boss, or to save up for the first two fights, and then use an action point in the third, fourth, and fifth fights (assuming a standard 5-encounter adventure).
Daily powers play this straight with many players as well; because they are usable only once per day (though they do reset), they tend to be saved for bosses. At low levels, you only have one, and thus often save it for the boss fight. At higher levels, you will have four daily powers, and possibly some daily utility powers as well, meaning that if you save them all for the final fight, even if you use them every single round in the fight, you still may not run out of them and will likely overwhelm the boss with insane firepower. Interestingly, many high-level monsters seem to be designed with the assumption that you'll drop a daily power in every fight, which is actually probably a good idea, because it helps you conserve healing surges for later in the adventure.
In all editions of D&D, many limited-use magic items such as scrolls, potions, and wands may become this. Players save them, and then eventually realize that they have saved them so long they have become useless.
Interestingly, in 3rd edition D&D, because almost all magic items can be bought or crafted pretty easily, this sometimes got reversed for cheap magical items; one of the most common accessories for experienced adventurers was the so-called healstick or curestick, a wand of cure light wounds which had 50 charges and thus could heal massive amounts of damage between fights at an extremely low cost. Once players got wealthy enough, they would start every fight at maximum hit points as a result, which lead to 4th edition allowing characters to simply heal for free between fights, and for limited-use healing items to heal using the same pool of healing as natural healing used, making them more of a convenience than anything else.
All editions of D&D suffer from the "5 minute workday" issue to varying extents in order to subvert this trope; essentially, the players unload ALL of their best daily abilities up front, and then immediately go rest, so that they can spam them every single encounter. This was a much worse problem in earlier editions of D&D, where there were many ways of hiding in a safe space under pretty ridiculous circumstances.
Avalon Hill's Third Reich (both the table-top and computer versions) has elements of this:
The double move: With a little judicious spending, it's possible to move twice in a row, which can be a huge advantage. The only problem? It tends to set up the other side to do the same exact thing, so most players will never use it unless they can be pretty certain of knocking a major enemy country out of the war.
American units: These are the best Allied units in the game, but they have a drawback. American units that get eliminated have to be rebuilt in the United States and then initially deployed to Britain (or France, in the unlikely event that France is still standing), but the United States can only initially deploy six units per turn, and those units cannot be strategically redeployed to any place outside of Britain until the next turn. So there's a temptation for the Allies to let the British carry the brunt of the fighting, since any British casualties can return to the front a turn earlier than any American casualties.
French and British units in the Mediterranean theater: This is the same principle as the previous point. British units are generally stronger than French units, but British units require two nine-factor fleets to be transported to the Mediterranean front, whereas French units require only one (assuming the French navy has been based in Marseille). So if the war in North Africa heats up while France is still standing (granted, it usually doesn't), there is a temptation for the Allies to let the French to bear the brunt of the fighting there.
Magic items in the earliest edition of The Dark Eye could easily end up being this, since with the single exception of the eponymous "dark eye" all example items listed in the rulebook, from the obligatory healing potion over a belt that would temporarily boost a character's strength to a key that could open any lock, were single-use only. (The dark eye itself was limited in a different fashion — it was a crystal ball magically tied to the site of its creation, so even if you ever found one you couldn't take it with you.)
In Warhammer 40,000 several armies, most notably the Dark Eldar and Inquisitors of the Grey Knights faction, have weapons or items which are "one use" or "One Shot". They usually have a disproportionally high power compared to a reusable weapon/item of similar effect (such as a weapon that can simply negate something's existence as opposed to a really good, but still avoidable anti-tank weapon). However their one use means that you have to pick and choose your moments and, on top of that, because of the dice-based nature of the game you run the risk of having it not do anything at all. Certain items are also force multipliers, meaning you'll be trying to squeeze all your troops into it's area of effect before setting it off, but this runs the risk of squeezing your army into one neat and tidy ball for your opponent's massive weapon.
Warhammer has a good number of one-use-per-game magic items that a player must carefully choose the right time to use. Frequently these will end up going unused in the hands of a cautious player, who is saving them for a later that never comes, just in case. Perhaps the most common such item in the 8th edition of the game is the Dispel Magic Scroll - a scroll which automatically dispels an enemy spell and stops it from working before it is cast. In previous editions of the game the Dispel Magic Scroll was ubiquitous — pretty much the only magic item that could be duplicated. This led to many players loading down their wizards with as many of the things as they could cram in, then using them liberally, to severely curtail the enemy's magic phase. This was rarely fun, especially if both sides were doing it, so in 8th edition the Dispel Magic Scroll has become a one-per-army item like everything else. Now that it represents your army's one chance to automatically counter a key enemy spell (other dispel attempts require the rolling of dice, and can fail) it has become a precious resource indeed. So precious that they frequently go unused nowadays.
Subverted in Numenera: One-shot items called cyphers are found all over the place, but PCs are only able to bear carrying two or three or a time. So regardless of how awesome a given cypher is, the system encourages you to burn them and grab new ones after every encounter.
Destiny points and, to a lesser extent, Force points in Star Wars: Saga Edition:
Destiny points are extremely powerful character attributes - they can be spent to make any attack an automatic critical hit or any enemy attack an automatic miss (even after the dice has already been rolled and the results announced), they allow your character to act out of turn or take damage, and they can be spent to immediately generate three less-powerful, but still useful Force Points. The downside? You only get one at each level up, with no way to obtain more. Due to their extreme power, players tend to stockpile them and not spend them unless the situation is truly desperate. Some GMs houserule a hard cap on how many destiny points a character can have at one time in an attempt to avoid this (and to prevent the players from taking out the campaign's final boss by using destiny points to score 5 critical hits before said boss can even act).
Force points allow a character to activate some special abilities, add 1d6 to nearly any d20 roll, and turn a fatal blow into a merely incapacitating one. That last one ensures that players always keep at least one on hand at all times. Because Force Points only regenerate at each level up, players usually stockpile a couple for emergencies and refuse to spend them until they're close to levelling up. An alternate, optional rule sees players get a far lower number of Force points (one for Levels 1-6, two for levels 7-12, and three for levels 13+) but have them regenerate daily. Though the game suggests using this rule for a campaign that uses Force points more frequently, the end result often sees less Force point usage, to the point where players under level 7 frequently won't use any Force Points at all, lest they be caught without one when a strong attack drops them to 0 HP.
Films — Live-Action
In This Is Spinal Tap, Nigel Tufnel has a six-string Fender bass guitar, still in wrapping, which has never been played. He says to Marty DiBergi: "Don't touch it! Don't even point at it!" Truth in Television: that instrument is a Fender Bass VI, of which only some 300 were ever made. They are Too Awesome to Use even in the Real Life. Only two are known to exist in that Sea Foam Green colour scheme.
Krull: the hero receives an awesome magical glaive weapon in the beginning of the film, but his mentor advises him not to use it until he needs it most. It sits on his saddle for the rest of the film until he faces the Big Bad.
Fate/Apocrypha features Karna as one of the Servants, who by extension has access to the Vasavi Shakti, the javelin of the Sanskrit god Indra which he was promised one use of when he shed his armor and earrings, which made him invincible. This javelin is capable of killing gods, but to activate it he must permanently give up those same items, going from immortal to a Glass Cannon.
In Fred Saberhagen's Books Of Swords trilogy and the sequel Books Of Lost Swords octology, Farslayer had this problem: its wielder could use it to kill anyone, anywhere in the world, even a demon or a god. The only problem was that it would remained lodged in the victim's heart, meaning that it would now be in the hands of whoever was nearest the victim when the Sword struck. It also leaves a trail pointing to you.
Invoked in Prince Caspian. Caspian is reluctant to use Susan's magic horn since there might be an even greater need for it in the future. Nikabrik points out that, by that argument, he will never use it until it is too late.
Sorcerous Overlord Longshadow provides a villainous demonstration of this trope in the Black Company series. He is recorded as hoarding numerous gewgaws, knickknacks, what's-its and thingamabobs enough to leave your jaw unhinged. None of which are given greater purpose than collecting dust, even after his armies have been nigh obliterated, his fellow (allied) Shadowmasters have been offed (partly due to his Chronic Backstabbing Disorder), and he has the weight of the manhood of an Indian-esque scaling the walls of his incomplete mega doom fortress.
The Lay of Paul Twister: In a flashback chapter, Paul Twister tells how he came to this realization. When he was abducted from modern-day Earth to a fantasy world, he was in his car at the time and it came along with him. Of course, In a World with no gas stations, this marvel of modern transportation technology turned out to be useless. In true video game fashion, it ends up being saved for the final boss battle.
This almost becomes the fate of Harry's Felix Felicius in Harry Potter and the Half-Blood Prince. Having won it on the first day of class, Harry goes most of the year not using it, except in Magic Feather plot to help Ron play well in their Quidditch match. All throughout the year, the notion of using it for various purposes crosses his mind, but he holds back, until he does eventually use it to gather an important memory from Professor Slughorn.
In Auction Kings, one seller brought in a motorcycle with only a couple miles on the odometer. This was the only time in the entire series that Paul was unable to test-ride a vehicle he sold.
The Dutch version of The Mole introduced "jokers" in the later seasons that players can use to nullify incorrect answers on the test that determines which one of them will be executed, and they typically can hoard them to use on future tests when the margin of error is smaller. Many contestants have ended up executed when they still had a joker or two (or three or even four!) in their pockets because they either thought they were safe and didn't need them or wanted to save the jokers for when they'd really need them.
The Amazing Race introduced the Express Pass in Season 17, which allows the team holding it to skip one task (or neutralize a U-Turn used on them) anytime in the first 8 legs of the Race. It generally averts this, as teams will use it the first time they think they're in danger of elimination (or on the 8th leg if they still have it at that point). However, in Season 22, Jessica & John won the Express Pass on the first leg and were actually eliminated without ever having used it because John insisted on saving it even when it was clear they were in last place and there was only one other team still racing.
Survivor introduced the Hidden Immunity Idol in Season 11, which can be played at almost any Tribal Council to be safe if one feels they are in danger. Many a contestant has gotten voted out with an idol in their pocket when they mistakenly thought they were safe for that round and decided to save it for later. The most infamous example was in Survivor: China where one of the contestants, James Clement, was in possession of two hidden immunity idols and was blindsided with both of them in his pocket. It was regarded as the dumbest Survivor move ever, until next season.
In the early days of 8-Bit Theater, Red Mage treats everything like this. Even his own spell slots. This nearly gets him burned to death on at least one occasion.
Weapons of mass destruction — atomic, biological and chemical weapons. They certainly are destructive and lethal, but their use gives a certain signal, and especially gas warfare is a signal of a really bad person. Using them also opens you up to retaliation in kind, often from someone who can afford to use a lot more of them than you can. Includes also dirty bombs — that is, radiological weapons. Especially the Genie nuclear air-to-air missile, intended to be used against Soviet bomber formations.
Rare coins and dollar bills:
The 2-dollar bill. Some people give them as gifts, knowing that the recipient will keep it for this reason. Even though they are rare in circulation, they aren't actually rare at all. The U.S. Treasury has been sitting on shrink-wrapped piles of them for years, but banks rarely ask for them. Strip clubs, on the other hand, loves to use them to make change as it encourages bigger tips.
On the other end of the scale are $50 and $100 dollar bills, to the point where most shops refuse to accept them. However, there is a good reason for this: the bills are worth so much that if a cashier were to attempt to make change for a $100 bill, it is likely that they would run out of lesser bills, so that the store cannot make any more change for the rest of the day. Also, larger bills like that are the main target of counterfeiters, as they obviously are more worth the effort.
To hard-core numismatists, Sacagawea and Eisenhower dollars are no different than the change we have in our pockets. However, there are other dollar coins made from precious metals that you would be an idiot to spend at face-value. A $3 gold coin (yes, they really exist) minted in 1854 and in near perfect condition (MS-67) is worth at least $95,000. A Flowing Hair Half Dollar minted in 1794 in MS-64 condition is worth over $450,000. There are even platinum coins out there. A platinum Eagle ($10) minted in 2000 is worth $7500 in perfect (MS-70) condition.
This also goes for the Japanese Ą2000 note. Just having one is a conversation point, and no one ever spends them if they can avoid it.
The British Ł5, Ł10 and Ł20 coins.
The Canadian one and two dollar bills are still technically legal tender, even though they were replaced by loonies and toonies over twenty years ago since they are cheaper to keep in circulation because they stay in good condition for decades longer than paper banknotes. The bills are now kept by people old enough to have used them when they were still in circulation. Collector's coins, put out every year or so, are also carefully hoarded, unless you've already got one, in which case they typically get spent.
The 500 Euro bank note.
The 5 Deutsche Mark bills used to be this before getting replaced by the Euro. It was rarely used, because there was also a 5 DM coin which was used much more widely.
For Brazil, there are the R$100 note and, more unusually, the R$1 notes. The former is rare for the same reasons as the American hundred-dollar bill, while the latter ceased production in 2005, and is now a rare item. In an inversion of the US$2 bill case, R$2 bills are ubiquitous.
Vacation days. At the beginning of the year, you use one or two here and there, in the summertime, you use them in batches for planned vacations (combined wisely with weekends of course), and then when summer is over, you brace yourself and won't use them unless it's an absolute emergency, since you will need them Christmastime. This is especially true, when the remaining days are less than 10, then you become a lion protecting her cubs. Throughout the year, a lingering fear is constantly present, that you will run out of them.
The Japanese in WW2 more or less hoarded their battleships for a decisive surface fight that never actually wound up happening. By the time they got to the point of desperation, the best use they had for the largest battleship humanity has ever built was as improvised land-based artillery.
Anyone who posesses an actual nihonto will attest to this. They're great swords, well made and quite beautiful, but they're no good for typical tamashigiri because they cost several thousand dollars.
A major debate among survivalists is situations in which, for example, you are stranded in a desert, and have a limited supply of water. Some say that conserving it is the best idea, others say that this is not the best idea, and you are instead advised to drink all the water you need. After all, hikers have been found dead from dehydration with water still in their canteens.
Metabolism is a miser. It never wants to waste a single calorie taken in, and will ask for more mere hours after getting some. So when the human metabolism, evolved as it was for a hunter-gatherer lifestyle where this made sense, meets the modern agri-industrial days of plenty, bad things happen.
Wedding dresses, which are typically used only for one occasion.
Movie costumes. They are horrifyingly expensive, because they start with a famous costumer, and a lot of money goes into their outer look, but they are often shoddily made, because they aren't intended for anything other than a brief scene. Sometimes they have fronts, but not backs, and other times, and actor is sewn into them, so they have to be taken apart after the scene is shot. Often they are cannibalized to become parts of other costumes for other films, but the most famous ones end up as museum pieces, because they are too awesome (and impractical) to be used as regular clothes.
The Yankees had the Joba rules, a set of rules for use of Joba Chamberlain, a pitcher that is supposed to be the next big thing that basically stated he gets an extra day of rest for every inning he pitched. It got annoying to hear after the first 5,000 times.
The 2012 Washington Nationals inverted this Trope with their star pitcher Stephan Strassburg. Coming off of Tommy John surgery, they used him normally until he hit a year-long "innings limit". In early September. And, no, they didn't use him in the playoffs. So while he got them there with ultimately a 4 game lead over the Atlanta Braves and a 1 game lead over the Cincinnati Reds (for Division and Home Field respectively), it came back to bite them when the Wild-Card-Winning St. Louis Cardinals dropped the Nats 3 games to 2 in the Divisional Round.
Wine collectors often buy extremely expensive wines and are reluctant to ever crack them open, because to do so would destroy the wine and remove it from your prestigious collection. Also, you never know if this event is really the best time to drink it. Since even the best wine will be vinegar after 100 years, you'd best drink it at some point!
Compulsive hoarders can abuse this trope regularly when it comes to storing things. People who suffer from this can never bring themselves to throw away things they no longer need or stuff they never use because they keep thinking that either they will need the item one day or will find said item too important to use.
Game theorist Avinash Dixit presents a solution to this problem, known in economics as the spongeworthiness problem, after an episode of Seinfeld in which Elaine contemplates the use of special contraceptive sponges she bought that later get pulled from shelves.
The Browning Automatic Rifle never saw much use in World War I, partly because it was developed so late and partly because the U.S. military feared it being captured and reverse engineered. By the time they did get to use it, it was impractical: too bulky to use as a personal weapon and with a magazine too small to serve the role of LMG.
Sex.com is the record holder for the most expensive domain name ever. The domain has changed hands several times for millions of dollars each time. Still, up until 3/25/2012, none of the owners had ever used it for anything more interesting than an ad farm, with no actual content or services of any kind.
The F-22 Raptor. It carries the most cutting-edge Air Superiority Technology ever made. It is all but invisible on enemy radar, and it has been known to amass kill-death ratios in simulated exercises approaching 200-0. It also costs a quarter of a billion dollars a pop. With such a prohibitive price-tag, and sensitive technology on board, the Air Force almost never actually deploys them to a combat zone for fear of losing one. It doesn't help either that it was built with the idea that it would be going against another advanced air force such as Russia or China, as opposed to Libya, where to have used the F-22 would have been complete overkill, especially considering the price-tag.
Collector items can become this. It can either be straight up due to the item in question being a one-use item that either can't be duplicated (most likely any sort of ancient liquor, as you'd need to wait the equivalent amount of time to get "back" what you lost) or the collector in question intends to sell it, but is intentionally keeping it to add to the value, as generally the older a collector's item gets, the more valuable it is. Stocks can function like this too, and if it's the latter reason, it's very rare that the collector will sell it at peak value, as he will probably only realise the peak after a steady decline has started, or sell it prematurely thinking it's the peak.
Blood type O-. You can donate to anyone you want because your blood doesn't screw with the immune system of others (which is why you can't donate to anyone with blood type B if you hold blood type A), but hospitals don't use it because no one can donate to others with blood type O- other than themselves, so they keep it to use it on people with blood type O-, or in emergency cases where they don't know your blood type and there isn't time to ascertain it. On the other side of the scale is blood type AB+: they can receive blood from anyone, but can't donate to anyone but themselves.note This is only true if erythrocytes are transplanted. If plasma is donated, it is the other way round because it contains the antibodies which cause clumped blood if they get into contact with the wrong antigen.
Skunk musk is so foul that even bears avoid skunks; however, a skunk can only hold enough musk for 5-6 shots, and it takes weeks to recharge. Skunks are reluctant to use their spray until the situation is desperate, and will threaten their opponents instead.
Car enthusiasts can inflict this trope on themselves. Depending on the type of car they own, they may go to extreme lengths to keep the car tuned up and/or make sure there is not a single scratch on the car, but they will barely even use said car. Some people have two cars to alleviate this problem; one car for everyday use and the other more expensive car just to show off to other people. When Top Gear did a piece on the history of the Ferrari GTO models the show couldn't afford the insurance to drive a 1964 Ferrari GTO round their track. Famous racing cars in general can become too valuable to race in historic competitions for fear of damaging them.
Expensive musical instruments, such as Stradivarius violins or '59 Gibson Les Paul guitars (see the Spinal Tap entry above), can become too awesome to play. Which is really sad, since they also do have legendary, beautiful sounds — otherwise they wouldn't be so expensive. And instruments played by legendary musician end up in cases in museums rather than actually being played by any one.
This is why vintage guitars has been designated as a "collector" or "player". A collector instrument is one that is often in close to pristine condition and all original parts. A "player" on the other hand will often be a bit beaten up (even if well kept an instrument will almost always receive some scratches and marks) and might have had some parts changed (in some cases for the better, perhaps a better bridge and tuners for intonation). Players will still fetch a big price tag (usually along the lines of higher end regular models to some custom models), but will be much cheaper. It's also common to use a very nice guitar/amp (say a '59 Les Paul and a '68 Marshall) in the studio, where the environment is controlled and the best sound is of greatest importance and for live use instead have a reissue model.
One of the reasons successful race horses are eventually retired and put out to stud. The owners cannot afford to risk them on the track any more.
Homework passes in elementary and middle school can become this. Some teachers give an option for students to use the passes for extra credit at the end of the year (usually all of the passes have to be given at once for this option) so if a student doesn't wind up using the passes to make up for an assignment, they don't go to waste. The has the side effect of encouraging students to actually do the homework and save the passes for the extra credit option.
Some argue that Bitcoin is fast becoming (if not already) this due to its appeal as a speculator asset, given the large fluctuations in the cryptocurrency. In other words, it's much more profitable to keep and hoard up bitcoins than to actually use them as currency.
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