What may have worked ten years ago, no longer does!
...and if it fails, too bad. You only get the one shot.
It Only Works Once is a method of defeating the bad guy which is completely useless in the following episodes. It could be a Forgotten Superweapon or other Applied Phlebotinum that cannot be replaced once it's used up. It might be an attempt to exploit an Achilles' Heel vulnerability that the enemy will correct or at least guard more carefully once it's brought to his attention.
Reversed, it is a common trope of cartoon series. The Big Bad will come up with some undefeatable plan that almost works save for some streak of luck on the part of the heroes (see the Road Runner shorts for some especially lucky breaks), but will never think of trying it again after being foiled the first time.
Occasionally a special attack that Only Works Once will end up being used in The Worf Barrage.
When you're getting near the end of a show or film and you know the trope will be averted because it's near the end and not a tragedy work, you're being Spoiled by the Format.
Never Recycle Your Schemes is a subtrope. Compare So Last Season, Forgotten Phlebotinum, Holding Back the Phlebotinum, No Plans, No Prototype, No Backup. See also Adaptive Ability, Reed Richards Is Useless, and the Disposable Superhero Maker. Most Wave Motion Guns apply a limited form of this trope by making its use prohibitively slow and energy-intensive, but the usual dramatic application is rather different. Often overlaps with Death-or-Glory Attack.
- The GeoGrey Sword in Digimon Savers; after its first appearance, it ceases to work on anyone, up to and including the villain in The Movie.
- In Digimon Xros Wars there's the digimemories which have the data of legendary digimons, and can summon them to use their abilities. But they can only be used once for each zone.
- Variation: Lelouch's mind control power in Code Geass only works once on any specific person. The duration can be permanent if worded correctly, but if the effect ends, that individual is never again affected by the power.
- Unless Cyber-Jeremiah shows up with his Geass Canceler: the power alters their brain permanently, even if it only has any effect temporarily, but once the effect is reversed they're freed up to have it used on them again.
- The Kido Cannon in Bleach: Memories of Nobody burns itself to ash after being fired only once.
- The Final Release of a Zanpakutō falls under this because after being used once the shinigami loses all of their powers.
- There's also Muramasa, main antagonist of the anime filler Zanpakutō Rebellion arc. Muramasa is a Zanpakutō spirit whose power is bringing other Zanpakutō spirits to life and turning them against their masters. He does this by tapping into their most suppressed instinct, and using it to control them. The only way to break the spell is for the Zanpakutō to be slain (which is difficult to reverse if it's by anybody aside from its master), but if they do, Muramasa's power won't be able to affect it a second time.
- JoJo's Bizarre Adventure: Straits/Straizo in Part 2 had the powerful Space Ripper Stingy Eye, an ability he witnessed in part one where a vampire can shoot fluids from the eyes at a ridiculously high velocity, allowing it to cut through flesh. The first time he fires it he misses a fatal shot at Joseph, but nicks his neck. The next time he tries it he hits a mirror reflection of Joseph and then the third time it is completely reflected, with Joseph lampshading that he only needed to see the attack once to know how to counter it, due to the predictability that Straits would go for the fatal shots in the neck and forehead again.
- Subverted in Part 1 where Jonathan is caught off guard by Dio's attack of the same kind, as the first time it was used he was plummeting off a cliff and didn't see it firsthand. The second time it is used he had no idea it was coming.
- The above two can also be grouped together, the attack ended up being fatal to Jonathan as the first real encounter with it, but the story of the attack was passed down through Erina to Joseph, her grandson. As a result it never succeeds from the start on Joseph because he already knew how the move worked.
- Part 3's Anubis inverts this trope. Along with its unique traits, its skill in swordsmanship is so extreme that using the same attack twice against it is completely ineffective.
- Later on in Part 7, during the climax of the D4C arc, Gyro uses the Super Spin Technique to attack Valentine. This attack rapidly ages cells to the point of death. Though technically successful, an imperfection in the steel ball cancels the perfect rotation, allowing Valentine to survive the attack. Gyro doesn't get another shot. Johnny later attempts the same feat, but Valentine's warning prevents the Dio from another world from suffering the same fate.
- Subverted in Part 1 where Jonathan is caught off guard by Dio's attack of the same kind, as the first time it was used he was plummeting off a cliff and didn't see it firsthand. The second time it is used he had no idea it was coming.
- The Gold Saints in Saint Seiya take pride in repeating how an opponent can only use a technique against them once, and then becomes ineffective. Their reasoning is that, having seen the attack once, they've learned how to avoid it. Sometimes the Bronze Saints are allowed to repeat this phrase, but only if their enemy poses no real threat whatsoever.
- Only problem is that Seiya insists in using the same technique over and over, initially not hitting his enemy, but eventually it does and he didn't change his technique, he's just doing it faster.
- Only SAINTS OF ATHENA have such a power or technique, as they learn to do it with their training. Seiya's case is always lampshaded as him going beyond the impossible to the point that his meteors are so numerous they turn into one big attack; cherry tapping up to eleven. Still, the dialogue fails to convey this realistically or seriously.
- One Piece:
- Numerous villains seem to just give up after an ass-kicking by Luffy and co. despite the fact that they could logically resume their activities after the Straw Hats have left the area. Especially since Luffy and company nearly never actually kill the Big Bad. Most of the time they go a ways to justify why the Big Bad doesn't do this, but occasionally they don't bother.
- First example: Captain Kuro. Kuro had planned to leave a life of piracy by instilling himself as a butler of a rich child. After a few years, he was going to have his hypnotist force her to write Kuro into her will, then kill her and take her money. Instead he gets beat up and forced back out to sea. Though he couldn't have pulled this trick again on the same island (and would need to adjust the plan for a lack of a hypnotist), no one else knew he was alive and he could have tried elsewhere. Yet he's still a pirate as far as we know. Later it's revealed that the Marines somehow learned that Kuro had faked his death, though exactly how is unclear.
- Next is Buggy, who had taken over a town. Luffy beats him and sends him flying. He could always just stay the course. However, Buggy being Buggy, he holds a grudge and starts following Luffy instead. This also happened to Alvida, who joined Buggy.
- Crocodile looks this way, since his loss of Warlord of the Sea status means he can no longer operate out in the open without drawing attention from the Marines, but his criminal organization still exists. A miniarc revealed that after Luffy defeated him, Crocodile lost interest in the outside world, which is why he doesn't bother escaping jail with most of the rest of his Officer Agents. However, when he heard about the impending war with Whitebeard and the World Government and Luffy showed up on Level 6 attempting to rescue his brother, he offered his power to help them escape, his interest rekindled by a chance to strike back at the pirate who ruined his dreams of becoming King. And with that pirate's death, he's ready to give it another shot; the next time Crocodile is seen after that arc, he has plans to head towards the New World again.
- On the topic of Alabasta, there's Nami's Clima-Tact; Usopp had made it little more than a tool for parlor tricks, but the Tornado Tempo was specifically described as an attack that can work only once. This is due to the attack relying on wound springs inside one of the 3 poles. Once it fires it looks like it would take significant effort to reload (think trying to re-coil a stretched out slinky) and many of Nami's attacks require all 3 poles so losing one means her fight is basically over regardless of if she's won or not.
Usopp's Instructions: Tornado Tempo packs a knockout punch. However, it is absolutely a weapon of last resort! You have only one shot! If you miss, it's all over.
- Brook's Devil Fruit grants him the ability to come back from the dead... once. Since his soul took too long to find his body, he is now a living, still killable skeleton. But with training, he has subverted the trope by expanding on his power, making its ability to revive him only one aspect of his powers.
- In the final episode of The Big O Roger Smith finally puts some of the pieces of the Myth Arc together and unlocks the Wave Motion Gun built into his mecha just in time to put an end to the Big Bad. Wouldn't you know: He missed, and firing the one shot burns the gun to a crisp.
- REDLINE: The president of Roboworld uses the Three-Point Disintegration Cannon to try to kill Funky Boy. Unfortunately, Funky Boy regenerates, while the Cannon needs two hours to recharge.
- Space Adventure Cobra: Cobra's arch enemy of the Three Sister's Arc, Crystal Boy, is Nigh Invulnerable to just about every attack Cobra used against him. Near the end of the Arc Cobra faces off against him and after a long fight he catches him off guard by launching his fake arm at him via the Psychogun, presumably killing him. When he appears in the Psychogun OVA Cobra attempts to kill him the exact same way only to have him catch the fist mid air and proclaim that the same trick wasn't going to work twice.
- In the first episode of the series, a hectic encounter with hostile aliens forces Space Dandy to reveal a decoration on the Aloha Oe that is actually an explosive powerful enough to an destroy an entire planet. If he had though it through, he would've realized that detonating it spells doom for everybody, including himself and his crew.
Dandy: I knew there was a reason I hadn't used this trick before.
- Ranma ˝:
- In a similar instance to the Saint Seiya example above, an OVA pitted (female) Ranma and Akane versus two powerful sisters (never happened in the manga). After getting creamed in their first match, the two leads train for a rematch. The sisters' ordinary attacks then prove ineffective against Akane (who has trained up to their level) and their special skills are useless against Ranma (who explicitly says, "Your wind attack ain't gonna get me twice! I've seen it once and it's easier to avoid it!")
- Turning the trope on the villain's favor, the manga confronted Ranma with the Musk Prince Herb, descendant of a dragon and master of chi techniques. When Ranma tried to use the overwhelmingly powerful Hiryu Shoten Ha technique on him, Herb recognized it and easily dodged it, since he had seen it many times before in the past and it was arguably part of his education. This was the same problem with Happōsai, who had once been on the receiving end of this technique (from a young Cologne) and already knew how to thwart it.
- Even further: when Ranma used the Parlay du Fois Gras technique on Picolet Chardin, it only worked for a few instants; both he and his teacher recognized the technique and immediately used a variety of defenses. Although Ranma tried to use new variations to get around these counters, each only worked once, until she was left with no way to attack her opponent.
- Shampoo once offered Ranma a packet of bath powder that would nullify his curse in exchange for a date. She learns soon after that the powder works only once, but leaves that part out when Ranma finally gets the powder.
- Any Pokémon with the move Overheat, though most notably Ash's Torkoal, could only use it once at full power. This has its roots in the games, where, while the move can be used multiple times, it cuts the Special Attack by half when it is used.
- Ash's Snivy's Attract only works once for an opponent. After that, they find a way to break through it.
- Tengen Toppa Gurren Lagann. During their first encounter, Viral makes a point of telling Kamina sneak attacks only work once.
- He's later proven wrong. By the Lagann Impact, no less.
- Practically speaking, Miroku's Wind Tunnel. It should be able to instakill every enemy the troupe comes across due to its ability to suck everything into the pocket dimension in his hand, but it takes Naraku one encounter to learn how to neutralize it... which makes sense, considering he's the one who put it there in the first place.
- Later, Sesshomaru discovers the hard way that the Tenseiga can only bring a single person Back from the Dead once.
- Negi's Pactio in Mahou Sensei Negima! allowed use of all his partner's abilities and Asuna's antimagic (to an extent) but was merely used as a tool to keep Rakan from using his own Pactio. And after that, it was canceled. Obviously for the sake of drama (such a game breaker power) but seriously, you would think something useful like that would be kept around. Although he could easily regain it by making a Pactio with someone else.
- The Mafuba/Evil Containment Wave in Dragon Ball was able to seal King Piccolo away in a rice cooker in his backstory, but fails all three times it's used on him or his son/reincarnation:
- Roshi tries to use it on King Piccolo, but it fails simply because he missed the jar.
- Tien also planned to use it against King Piccolo, but in the manga practicing the technique broke the jar before he could even try. In the anime he gets a chance to try it, but Drum jumps in front of the wave himself and King Piccolo destroys the jar before Tien can even seal him.
- Kami tries to use it on Piccolo (so he can stop him without killing him and thus himself), but Piccolo just turns it on him, mentally gloating, "If you thought this incarnation would be beaten like the last, then you have not thought!"
- In Dragon Ball Super, Trunks and Mai attempt to use this this skill on Zamasu, unable to beat the immortal god by himself or with Goku and Vegeta's power. However, because they forgot the seals to prevent escape, Zamasu's able to escape and flips the hell out.
- Likewise, it's revealed at the beginning of Dragon Ball Z that Shenron, and the Earth's Dragon Balls by extension, cannot grant the same wish twice; for example, if a person who has been already been resurrected is killed again, the person in question will be Killed Off for Real. Porunga, and the Namekian Dragon Balls by extension, have no such limitation. When Dende is brought in to replace Kami, this limitation is removed.
- Much like the Real Life example below, The Familiar of Zero pulls this with the Wand of Destruction. Only Saito can use it, and it only works once. It's really an M72 LAW rocket launcher and it has one shot, so when Longueville aka Fouquet tries to use it on Saito, it doesn't work.
- Human transmutation in Fullmetal Alchemist. That's because you have to give up your ability to use alchemy to do it, plus the person who you're bringing back has to be trapped at the gate (and thus not actually dead), plus your souls have to be linked so that you can return through their gate once you've given up your own.
- Izanagi, one of the Mangekyou Sharingan's powers lets the user cast an illusion upon himself making reality a dream and thus letting them escape life-threatening situations. However, the eye shuts permanently after it is used once.
- Deidara's "ultimate art" C0 involves using himself as a bomb. Too bad for him, Sasuke had just made in advance an ultimate escape plan for such an occasion.
- The Bartolls of the Super Robot Wars Original Generation OVA series worked on this trope - should an attack kill one of them, they would instantly adapt to it and find ways to dodge it or create ways to protect themselves. By the end of the second episode, Cybuster's forced to use CyFlash and the SRX is forced to use the Hyper Tromium Cannon just to wipe out a small army of them.
- The Gravity Cannon, from Zoids: Chaotic Century, only had three shots available, one of which had to be a test-fire. It didn't work. A fourth shell is later created, it still doesn't work.
- In Gundam Build Fighters, the Star Build Strike's Absorb Shield wasn't designed this way, but that tends to be how it works out in practice. As the name implies, the shield opens up and absorbs any beam attacks that come its way, then uses the energy to power some rather impressive Limit Breaks; after its spectacular first use, most of the smarter fighters (and this being the World Championship, that meant most of them) realize what's going on and go out of their way to disable the shield first or attack with solid projectiles like missiles that can't be absorbed.
- During Kinnikuman's fight against Atlantis of the Seven Devil Choujin, the ghosts of the previously killed Devil Choujin interfere, forcing the Justice Choujin to use a magic glass to become spirits and stop the interference. When Sunshine and Ashuraman use a similar trick during their match against the Machine Guns during the Dream Tag Tournament, the other Justice Choujin try to use the glass again, only to be rebuffed by the Mountain, who knew they were coming.
- In Fairy Tail, Natsu states his secret weapon against Zeref is this. Because it's the last of Igneel's power, he has no way to regenerate more of it once it's used up.
- In Kuroko no Basuke, this is the critical drawback of Misdirection Overflow. After its effect wears off, not only will that technique not work anymore on the team it was used on, but that team will also become immune to the most basic of misdirection techniques. It's described in-universe as "performing a trick while simultaneously showing how it's done."
- An Ultimate Marvel comic included Tony Stark curing Bruce Banner of the Incredible Hulk. The catch was that if the Hulk returned even once, its physiology could adapt and the cure would never work again. (See Doomsday, below) Predictably, by the end of the comic they are placed in a situation that requires the return of the Hulk.
- In comics, the monster Doomsday (who once killed Superman) had "evolution" powers, such that he could adapt to counter attacks once used against him — i.e., having once been beaten by a Green Lantern's ring, he became relatively immune to its power. In Superman/Doomsday: Hunter/Prey, the Radiant's energy attack which killed Doomsday in the past no longer has any effect on the creature when the recreated Radiant tries it again on him.
- Superman's revival after his death at the hands of Doomsday is considered this because of the circumstances behind it, involving a certain revitalization chamber and, possibly, Jonathan Kent having a near-death experience with him.
- Similarly, the DC Villain Calculator (before he was revamped as an evil Oracle equivalent) had an ability he'd use after each of his losses to a hero to "turn defeat into victory". He'd hit a button on his costume, which would render him immune to the powers of the hero who had just beaten him. Unfortunately, the DCU has an inexhaustible supply of heroes, so it never did him much good.
- In Fantastic Four, many of Reed Richards' attempts to cure The Thing have been of the only-works-once variety. These always come with a reversal method which Ben will inevitably use, sacrificing his humanity to stop the villain.
- When Kristoff Vernard was uploaded with Doctor Doom's memories to take his place after his apparent death, he decided to attack the FF by reusing an old plan to send the Baxter Building into orbit, reasoning that it had only failed the first time the true Doom attempted it because of the treachery of Namor; the plan failed again, but only because Kristoff's uploaded memories didn't include the Invisible Girl's ability to generate forcefields, allowing the FF to survive the building exploding in space and return to Earth.
- This trope is used as an actual story element in Runaways. Nico's weapon, the Staff of One, can cast any spell whatsoever but then can never cast it again. (Attempting to repeat a spell results in random effects.) It essentially serves as a leash to her otherwise godlike Green Lantern Ring powers. However, it turns out that she can only use each specific spell with a specific code word once; in a team-up with the Young Avengers, she was able to cast the same spell repeatedly by running through The Vision's language banks, while on another occasion she was able to 'reuse' a 'Freeze' spell by instructing her enemies to freeze at a specific temperature.
- In Paperinik New Adventures' fourteenth issue, a shadow creature can only be destroyed by a weapon created specifically for the job; the heroes, however, didn't have enough time to manufacture more than two charges for the weapon. As Paperinik puts it: "Be careful where you aim, you won't get a third shot."
- The original 40s Captain Marvel once fought a character that could cast any spell - once. He also had one, and only one, weakness. Their fights consisted of the two of them flipping through notebooks that listed everything they had tried so far, trying to come up with strategies.
- This ended up happening by the eighth or so issue of The Amazing Spider-Man. In the Vulture's first appearance, Spider-Man took him down by simply clipping his wings with a device designed to cancel out the magnetic harness that allowed him to fly. Not so in their second encounter, where the Vulture puts in a fail-safe to get around this, and sucker-punches Spidey the minute he isn't looking.
- Similarly, after being blinded with a squirt of webbing, Doc Ock started treating his glasses with a non-stick coating.
- Spidey once came across Stilt-Man wreaking havoc. He was disappointed, as the villain had designed a mask to keep Daredevil from hitting him in the face with his stick. Spidey just webs him to a lamppost.
- In an old Marvel Team-Up issue, Black Panther concocted a super strong web fluid to hold Stegron, a villain that had previously broken out of Spider-Man's webs. It was stated that the new serum was very unstable, and Black Panther himself warned Spider-Man that it could only be used on this one occasion.
- The Martian Manhunter once beat Despero with his innate Martian power to make someone believe that they're experiencing their most fervent desire. He'd never mentioned this power before and would never use it again, because, he explained, using it was so stressful that any one Martian could only do it once in their life. (Focusing on the pathos of his decision to use a power that his culture considered the ultimate gift to give a loved one to defeat a rampaging villain helped gloss over the Ass Pull.)
- In an issue of Uncanny X-Men Rogue absorbed Nightcrawler's powers and defeated Nimrod, the mutant killing robot from the future, by teleporting a chunk of his body away. The next time the X-Men fought Nimrod, Nightcrawler simply tried the same trick again, only to discover that Nimrod had adapted himself so that not only did it not work but the attempt messed Nightcrawler up quite badly.
- Similarly, Sentinel robots in general had the ability to learn from experience (and transmit this information to other Sentinels), so a trick used on a Sentinel wouldn't work again on any Sentinel. Their ability to physically adapt to is more limited than Nimrod, so anything that beats a Sentinel through brute force will usually still work.
- In Marvel's Heroes Reborn arc Doctor Doom had guard robots that had this programmed into them.
- Marvel villain Ultron tends to come back whenever he's destroyed, now with immunity to whatever wrecked him the last time.
- Doctor Strange once was turned into a vampire by Dracula, who boasted that since Dracula rules over all vampires, Strange was unable to attack him. Indeed, try as he might, Strange could no longer call upon his usual sources for spells: Aggamotto, Cyttorak, Watoomb, etc. In desperation, and with effort that nearly killed him, Strange called out the name of God.
- Jimmy Olsen once discovered Superman's secret identity. At the end of the story, Superman used a combination of heat- and microscopic-visions, focused through a space jewel and directed through Jimmy's eyes, to burn out the portion of Jimmy's brain which held that piece of information. Superman lampshaded the trope by telling Jimmy that he could only perform this trick once: if he ever tried it again, he'd short-circuit his vision powers.
- When Superboy was dying after a particularly strenuous fight Robin was able to find a cure in one of Lex Luthor's secret labs. However the cure could only be used once and any attempt to use the same concoction again after having used it once would kill Conner.
- Becomes a long set up Brick Joke in Transmetropolitan. Spider cloaks himself in source gas (a substance that records sounds like a microphone because reasons) before his first interview with the Smiler in order to catch his campaign in a lie. The second time he goes in, The Smiler's wise to the trick, and disables ALL of Spider's recording equipment. At the end of the comic, Spider pulls the trick a third time, and this time it works, because Spider's "been showy" with guns, and the Smiler only had him searched for weapons.
Spider: The first trick I ever pulled on you, Callahan. Source Gas. I'm soaked in it.
- The Astro City "Dark Ages" story arc featured the Innocent Gun, a powerful mystic superweapon that was left behind by alien Precursors to be used to protect humanity from a vaguely unspecified future threat, and was crafted so that it could only be used once. Unfortunately, The Lancer ended up using it against another Big Bad, tearing a hole in reality and leaving the gun unavailable for future use.
- The reason why Diabolik and inspector Ginko don't bother reusing plans and gadgets: the next time the police will have figured out how to counter Diabolik's tricks, and Diabolik will know how to get around the counter, as shown by Diabolik's perfect masks (one of the rare tricks he does reuse: the police checks faces multiple times if they even suspect he's around, and sometimes Diabolik can pass through the checks if the circumstances are right). However this is valid only if the opponent knows what happened, as otherwise they can't figure a way out of it.
- In one of the Legion of Super-Heroes try-out issues, one of the would-be Legionnaires was a woman called X-Bomb Betty, who had the power to "create an explosion of 150 million megatons". When they asked her to demonstrate this she got a panicked look and said "But ... But I can only do it once!"
- Rosario Vampire: Brightest Darkness Act III: While the group is fighting Kuyou in chapter 41, Mizore and Kurumu manage to land a blow on him with their duet. In chapter 42, when they try the attack again, Kuyou isn't about to let it happen twice and disrupts the attack by throwing Moka at them.
- Squirtle in Ashes of the Past decided to one up Gary's Blastoise and his Mega Evolution and created Squirtlite, a Mega Stone for Squirtles. That's right, Squirtle created his own Mega Evolution. However, upon reverting back to normal the Squirtilite explodes in a massive burst of water. Averted as Squirtle can simply create another one until he figures out how to stop the Squirtlite from destroying itself after use.
- Marionettes: The first time Trixie faces Gear Shift and Cover Story, she covers the floor with ice to make them slip. In their second encounter, when she tries it again, they're wearing winter horseshoes that allow them to walk on ice.
- In an AU retelling of the ending of My Little Pony: Friendship Is Magic episode "Bats!" entitled "You Look So Sexy This Way", it's revealed that the spell Twilight used on the vampire fruit bats can only affect a subject once. However, the attempt to return Flutterbat to normal only restored Fluttershy's senses, leaving the rest of her still a batpony, and as Fluttershy receiving the rebound from the bats counting as being cast, the spell would no longer work on her, leaving her a batpony permanently.
- The omnipotent Oracle from Aladdin and the King of Thieves is "bound by the Rule of One: one question, one answer". She knows everything and will answer one question to any person who asks. After, she will never answer another of their questions (Much to Iago's frustration).
Jasmine: What were they after, the gifts?
Aladdin: Not all the gifts. This is what the King of Thieves wanted. (Holds up the mysterious scepter he wrestled from the King of Thieves during the chaos)
Iago: With all the other great stuff in here, why go for this thing?
(Suddenly, a blinding light emerges from the staff and it floats out of Al's hand. A voice rings out as a visage of a woman appears in the air)
Oracle: Your question is mine to answer! The King of Thieves sought my sight to find the Ultimate Treasure.
Iago: Did someone say "treasure?"
Genie: Hmm...Looks like an Oracle.
Oracle: I see all that has been, and all that will be.
Genie: Uh oh, uh oh, definitely an Oracle, tells the future, uh oh. (back to normal) Girlfriend, where were you registered?
Iago: Okay, you know all, so tell all. Where is the treasure? You know, the ultimate one?
Oracle: I am bound by the rule of one. One question, one answer.
Iago (frustrated): I only want one answer! WHERE IS THE ULTIMATE TREASURE?!
Oracle: You have already asked your question.
Iago: You mean before? Oh, uh, that wasn't a question! That was uh...thinking out loud!
Genie (grabbing Iago): VERY loud!
- Suicide Squad: Hell to Pay features a 'Get out of Hell' card as the main plot point, hinted to be the only one in existence and sought after by multiple dying and concerned about death parties to bypass punishment in death. It ends up being used up by Bronze Tiger when Deadshot leaves it on his dying body, though Amanda Waller is initially unaware of this when Deadshot gives it to her, she finds out in the tie-in comic that she had been duped. The comic focuses on her attempt at finding the second best thing available, a Key that also bypasses eternal damnation but doesn't necessarily sends someone to Heaven like the Card, and its also even harder to find.
- IN Final Fantasy VII: Advent Children Complete, Cloud Strife uses Omnislash in an attempt to finish off Sephiroth the same way as he did in the original Final Fantasy VII. Unfortunately for him, it backfires spectacularly, because Sephiroth is more than ready this time. Instead, Sephiroth's the one who makes a repeat performance by skewering Cloud through the stomach like he did during their skirmish in Nibelheim years before when Cloud goes in for the final slash. Sephiroth even takes the time to mock him for it, before showing his wing and stabbing Cloud multiple times in mid-air with Octaslash.
Sephiroth: "Is this the pain you felt before, Cloud? Let me remind you. This time you won't forget."
- Jack Sparrow's pistol in Pirates of the Caribbean: The Curse of the Black Pearl. When he was marooned, his former crew gave him a gun with one bullet to kill himself with. Indeed, he only fires the gun once in the film.
- Dodged around like an Old School Dogfight in Star Wars, when the Empire makes a new Death Star that, when completed, will be immune to the tactics that allowed the destruction of the previous one—unfortunately, it's only half finished when the heroes get to it, and they simply have to repeat the same "single ship in a tight corridor" tactic inside the weapon to launch torpedoes into the core. That goes out the window when they find that the villains put up a force field around it. And the force field projector was heavily guarded. Sure, the Rebellion would have a shot if they destroyed the shield generator...but they weren't in very good shape. There's the indigenous population of the moon it's on, but they're just Ewoks, what could they...shit.
- In Gojira, the Oxygen Destroyer is a one shot weapon used to kill Godzilla, and its creator ensures that it can never be reproduced by destroying his notes and killing himself. In Godzilla vs. Destoroyah, the device turns out to have mutated dormant Precambrian organisms into another Kaiju, leading the humans to come up with an elaborate plan to lure Godzilla into a fight with it.
- In the first of the films featuring Mechagodzilla, Godzilla was able to defeat his Evil Knockoff by tearing off his head, removing the controls and cameras that let the mechanical monster keep moving. The second time they faced off, Godzilla repeated the move, and was shocked when a second, smaller head emerged from the gap and blasted him with lasers.
- In Tremors, each trick used to defeat a monster will not work on the next one, because the creatures are too smart and adapt just too damn fast. The trend continues to reappear throughout the sequels.
- In Krull the seer known as the Widow Of The Web can protect vision seekers trying to enter her domain, in the center of a giant spider web, by turning over a large hourglass which immobilizes the giant spider guardian while the sands fall. We learn that leaving is impossible, because "it can be turned only once. That is the lure of the web."
- Richard Donner's cut of Superman II averted this trope by applying the same time travel reset button as the first movie, only in an even stupider way. More to the point, it links the freeing of the Phantom Zone criminals to Superman's use of this in the first movie tying into a warning Jor-El had given him about playing god with time. Superman did it the second time to fix the original mistake.
- Back to the Future Part III: Mad Dog has a gun that Only Works Once hidden in his hat and is foiled when Marty uses a Frisbee Pie Pan to deflect his one and only shot.
- The aptly-named "Henshin One-Shot" from the Non-Serial Movie of Kamen Rider Faiz lets a normal human henshin into Kamen Rider Kaixa exactly once. And that is because instead of the user suffering the after-effects, it dissolves the Kaixa Gear by overclocking.,
- Tony's badass wrist-lasers in Iron Man 2. Justified when we see Tony eject a pair of smoking doohickies from his gauntlets after firing the lasers. The single shot clearly burns the doohickies out, leaving him physically unable to use the weapon again at the time. Since he doesn't grab a new pair of doohickies out of a storage compartment, we can assume that re-readying the lasers requires more than a simple doohicky swap. Doohicky. Lampshaded by Tony himself when Rhodey says he should have led with that: "It's a one-off."
- In Man of Steel, the first time Superman and Zod fight, Zod's helmet gets broken and subjects him to Sensory Overload. By the time they have their rematch, Zod has learned to focus his senses.
- Mentioned in Mud. Mud was bitten by a snake as a child and had his life saved by having an antidote administered in time. Unfortunately since the antidote is made of horse blood, it's something the body will recognize as a foreign material after being administered once and reject...meaning if bitten again there will be no way to save him and he will die.
- The Amazing Spider Man 2: During his first battle against Electro, Spider-Man hits him with water, defeating him. By the time Spidey uses the trick again, Electro had already figured out a way to create a barrier to protect himself.
- Pacific Rim: This is actually the main reason Gypsy Danger's Armsword is used as a secret weapon. The Kaiju are all connected, with information one wave learns during their attacks sent back to the Kaiju leaders while designing the next waves. This allows them to analyze the earth tech and lets them come up with ways to neutralize them. It is this, combined with the increased number of attacks, that puts humanity in the bind that it is in by the movie's start.
- In Gamera vs. Barugon, the humans goad Barugon into firing his rainbow beam at a giant mirror, which bounces back and knocks him down. When the humans try it again, Barugon realizes what is going on and instead attacks them physically. He doesn't use his rainbow beam for the remainder of the film, except once out of desperation when Gamera kills him.
- Brought up in Species II with Sil/Eve's alien race. If they survive being exposed to a disease, after healing, they immediately develop an immunity to it, leaving it ineffective later on.
- In Dragon Bones, the heroes defeat the villains by killing Oreg, who is sort of a Genius Loci to castle Hurog, while the villains are inside castle Hurog. The castle collapses. This obviously only works once, as Oreg is no longer bound to the castle, so even after it's rebuilt, it can't be repeated.
- Piers Anthony's Xanth series had the character Surprise Golem that had the magic talent of all magic talents. Her talent is to have whatever talent she wants at the moment. It was soon discovered she could only use each talent once, but she could achieve the same results by using variations. Which makes it not much of a limitation at all, though some specific effects she might want to produce will naturally have more variations available than others.
- In The Dastard Surprise finds out that she can perform the same spell twice with a significant period of time between the two only to have her discovery erased from time by The Dastard.
- Talents themselves are a form of this in Xanth. Each person has a unique magical talent, and it's strongly implied (if not outright stated) that talents will never reoccur. Once a person with a specific talent dies, no one else will ever have that specific talent ever again. Talents can overlap in their effects (with Surprise's talent, by definition, overlapping with everyone else's), but no two are ever exactly the same.
- This is how all of the Adepts' spells work in Anthony's Apprentice Adept series, with the same variation loophole.
- In Edgar Rice Burroughs' A Fighting Man of Mars, the hero obtains invisible items from the villain for some effect. However, they lose them. You see, the invisibility was always in effect.
- In the New Jedi Order series of Star Wars novels, someone comes up with the brilliant idea of using the Centerpoint Station superweapon to destroy a Yuuzhan Vong fleet. Unfortunately the heroes get righteous on the guy trying to fire the weapon, and cause him to misfire. The weapon destroys a major Galactic Alliance fleet, and Centerpoint powers down, unable to be used ever again.
- A milder version in the same series, Jedi Knight Corran Horn has a "dual-phase" lightsaber, which allows the blade to extend in length. At one point, he surprises one of a pair of Yuuzhan Vong warriors by suddenly extending the blade, impaling him. He monologues to the other warrior (who may or may not have been able to understand him) that he knew he'd only be able to use the trick once, and chose to use it on the obviously less-skilled warrior, since he'd be more likely to fall for it.
- In John Varley's novel Millennium, once a time traveler visits a time, that specific time period from arrival there to return to your own time can never be accessed again.
- In On Basilisk Station, we are introduced to the grav lance, which allows even a light cruiser to take down a superdreadnought's sidewall, but has a very short range, a quarter that of standard energy weapons. Getting it to work requires immense sneakiness and the enemy not looking out for it. It works the first time because the OpFor was not expecting it, but in subsequent exercises the other side knows how to look out for its attempted use. It is these repeated failures that get Honor the eponymous Reassigned to Antarctica. In the final battle against a Havenite Q-ship that outmasses even a super-dreadnought, she manages to pull off another successful use.
- This is stated by Harrington to her students concerning her escape from Hades: the stunt she pulled to take out the State Sec convoy coming to retake the planet had so much that could have conceivably gone wrong, depended on the enemy being extremely sloppy in monitoring their sensors, relied on having detailed information regarding their approach that would be near-impossible to have in any other situation, and she had absolutely no other choice except to try it.
- Subverted in Storm From the Shadows, as the Mesan plan involving New Tuscany is, and is lampshaded as, a repeat of the plan used in Shadow of Saganami. However, the second attempt succeeds in its intended goal of provoking a war between Manticore and the Solarian League.
- A version of a bluff that only works once in Harry Harrison's Invasion: Earth. When the crew of an alien ship threatens to drop radiation bombs on Earth cities, the military replies that they have a secretly-developed laser weapon trained on the ship. The aliens try to call their bluff, but their ship promptly explodes. Turns out there is no laser weapon after all, but the soldiers simply planted charges on it earlier (interestingly, no one mentions the problem of a ship filled with radioactive material exploding in Earth's orbit). The remaining alien ship, after a few more words, wisely decides to leave and not challenge the bluff.
- Ender's Game has a strategy winning a training battle that is discussed to Only Work Once (it is technically an exploit of the battleroom rules). It works. A similar strategy comes into play in the end battle, recalling that moment.
- Ender is constantly challenged by the teachers, who keep putting him in situations that prevent the use of old tactics, necessitating him to come up with new ones on the fly. Not only that, but the other armies keep adopting his tactics, so he can't use the same ones anyway.
- Leprechauns in the Fablehaven series cannot be caught by the same trap twice. Patton Burgess not only caught one five times with five different traps, he had more traps ready for anyone who wanted to try it.
- In William R. Forstchen's Union Forever, a large naval battle between the Cartha led by Cromwell's ironclad Ogunquit and the Roumans led by Keane's hastily-constructed ironclads is ultimately won by the latter despite the former seemingly winning moments before. Why? Because reinforcements arrive for the latter in the form of what appears to be a gigantic ironclad with three long-range guns that look like they could turn the Ogunquit into wreckage. In fact, it's a barely-working small single-cannon ironclad with bits of metal and wood attached to the front and sides to make it look larger and wooden logs sticking out to make them look like cannons. It's specifically stated that this trick will not work again.
- This is a matter of some contention among the The Lord of the Rings fandom, among whom there is a vocal minority that considers Aragorn's use of a seemingly invincible undead army in only one battle (rather than throughout the war) to be a Headscratcher verging on a Wall Banger. Debates about whether the Exact Words of their oath would have allowed him to demand longer service from them can (and have!) gone on for dozens of pages in various internet fora. The popular consensus is that the undead army was not magically compelled to obey Aragorn, but did so voluntarily as he was the only one who could release them to pass on to a more standard afterlife. If they'd gotten it into their heads that he did not intend to release them, they could very well have gone over to the other side, so he decided that it was better to be safe than sorry. YMMV on whether this explanation makes this a legit example or is merely a convenient bit of Fan Wank. Regardless, they demanded to be released after a single battle, and he complied.
- In the ninth Ciaphas Cain book, an Imperium astropath discovers how to project a psychic field that jams the Tyranid Hive Mind, turning the tide of a major battle. Unfortunately, the strain burned out the captured Tyranid cortical node that was generating the jamming signal, and it will be very hard to find another one so nearly intact.
- Biggles found himself fighting Sky Pirates targeting bullion shipments in Biggles and Co. The first time they hit his aircraft, he thwarted them with a false floor in the aircraft and some decoy crates full of lead... with some explosives wired to go off when the lid was lifted. The second time it happened, the air pirates immediately went for the secret compartment... And got another load of lead ingots because he'd put the real gold in the main cargo hold. The third time, the now very annoyed air pirates discovered they'd forced down an unloaded decoy aircraft. That didn't work quite so well because the air pirates had an inside source who'd hidden a smoke bomb in the latest consignment.
- In Romance of the Three Kingdoms Zhuge Liang uses the Empty Fort Strategy, but then claims it to be this. Specifically, he orders his few hundred soldier to dress as civilians and all the city gates to be thrown open. Sima Yi is wary of Zhuge Liang's (entirely fictional) strategic brilliance and assumes it to be a triple bluff as Zhuge Liang's plans never leave his army open to this kind of risk. There are no historical records of this, however. Zhuge Liang's campaigns were poorly planned and executed and Sima Yi didn't know Zhuge Liang's modus operandi well enough for a plan that relied on him knowing it to work.
- Early in the Shannara series, Allanon mentions that certain powerful works of magic can only be performed once and then never again. This is the reason why the heroes of the various books have to spend so much time hunting down or protecting one MacGuffin or another - if, e.g., the Sword of Shannara goes missing, you can't just forge a new one to replace it.
- In I Shall Wear Midnight, Tiffany is told that while the Cunning Man has been defeated before, learning how it was done won't help her and she'll need to device her own strategy against him. The reason is that he won't fall for the same trick twice - he's cunning, after all.
- The television series V (1983) was premised on this. The red dust which was all-powerful in stopping the Visitors at the end of the V miniseries was suddenly found to be ineffective in warmer climates. Also, re-application of the red dust wasn't an option since it was found that repeated exposures to the virus could be deadly to Earth lifeforms too over time (as opposed to instant death for the Visitors).
- The "new" series of Doctor Who started its first season finale with Captain Jack Harkness using a gun with only enough power for one shot to disable a Dalek warrior.
- However, he still uses it several times in "Journey's End" and "The Stolen Earth." Maybe he charged it back up...
- The gun was originally a kitbash. He obviously had time to refine it and get it working properly in the two year interval.
- Similarly, the power the Doctor gains over the Carrionites in "The Shakespeare Code" when he uses the species' name to banish one of them only works once. Oddly, though, it only works once AT ALL, rather than only working once on each member of the species.
- Rose absorbed the Time Vortex in the season one finale, effectively making her a God, allowing her to reduce the Daleks to dust with a wave of her hand. However, the side effect was that it very nearly killed her, and caused the Doctor to regenerate after he absorbed the energy from her.
- However, he still uses it several times in "Journey's End" and "The Stolen Earth." Maybe he charged it back up...
- iCarly: In his first episode, Carly, Sam, and Freddie realize that all they really need to do to stop Nevel is tattle on him to his mom (since he is only 11). This is handwaved in his next appearance where they mention that his mom is going out of town and will be unreachable for a while. After this, it is never brought up again.
- In Tomica Hero Rescue Force the team combine all their vehicles into Great God Striker and use it's Super Final Rescue to destroy the Big Bad Batsu. Unfortunately it fails.
- In Star Trek: The Next Generation, the Borg have the ability to adapt to phaser frequencies after a few shots. The obvious workaround for this is changing the phaser frequency to something they haven't adapted to. The Star Trek: Elite Force games explicitly addressed this issue by introducing the Infinity Modulator (or I-Mod) gun, which changes frequencies too quickly for Borg to adapt.
- In the first level of the second game (based on the last episode of Star Trek: Voyager), the Borg adapt to the I-Mod as well by using a jamming field specifically designed to stop the I-Mod from firing. The player is forced to do the mission with regular weapons, using shots sparingly.
- The I-Mod actually infinitely randomizes the frequency to such an extent that the Borg can't even adapt to the randomization algorithm normally used by phasers.
- In the series itself, much is made of this trope when anyone is simply planning on fighting the Borg. They know that any possible advantage they can come up with will result in the Borg adapting to render it ineffective quickly afterward. Thus, they often hold back the advantage until it is most likely to be needed.
- Obfuscating Stupidity as a strategy in social game shows like Survivor. Part of the reason it only works once is that it relies on people not knowing who you are and only seeing the mask you put on in front of them. If say, you do this, get to the end or win, then return for an all-stars season a year or so later, your fellow players would know that you're not as dumb as you look. If you jump from one season directly to the next (such as Amanda&James, Rupert, Russell Hantz), then you'll still have the advantage of being unknown to your fellow players. That is, however, assuming the players are smart enough to see through it all. (Part of why Rob was able to get an easy victory in Redemption Island was because all his tribe members except himself and Kristina left their brains at home and thought Rob was going to take them to the finals.)
- This was also Russell's downfall in said season. The first two times he played, he was unknown to the rest of the players. When he returned for Redemption Island, he wasn't put on the "Stupid" tribe and they saw him doing exactly the same thing.
- Reaper had Sam, the main character, use vessels to catch escaped souls from hell. Each week's vessel was different, being an item related to what the escaped person had been sent to hell for.
- In Power Rangers S.P.D., Kat is given a special Morpher that allows her to transform, but only has one charge. She takes it and goes into battle as the Kat Ranger for the first and only time. Note that, in Tokusou Sentai Dekaranger, Kat's counterpart, Swan, has different reasons for her Ranger form, Deka Swan, to be used. And she obviously shows up in Kaizoku Sentai Gokaiger.
- In Tensou Sentai Goseiger, Robogog's ultimate weapon was a world ending Wave Motion Gun called Calamity Destruction, but it could be used once, and thanks to Buredoran, who intentionally didn't seal Gosei Knight's morpher completely, Gosei Knight was able to block the blast and stop it from destroying the world, leaving Robogog furious that his ultimate weapon had been wasted.
- In Wizards of Waverly Place, Alex defeats Franken Girl, the monster Justin created to guard his bedroom, after finding out that Justin installed his own laptop as brain and tricking the monster into shutting itself down with the "Control", "Alt" and "Delete" keys. Unfortunately for Alex, Justin brings Franken Girl back to life and adds a spell lock preventing Alex from using the same trick.
- In the first season of Workaholics, the guys got rehired after threatening to expose their boss' illegal business practices. This is never, ever brought up again, even in the numerous following episodes where she bullies them or makes their lives difficult in some way.
- In an episode of Andromeda, the Nietzscheans are trying to erase the AIs of captured High Guard warships. They have finally created a device that can do that without any physical damage, and manage to delete the AI of the Wrath of Achilles. Dylan captures the device and keeps it in storage. A year later, a rogue AI named Gabriel hijacks a newly-built sister-ship of the Wrath of Achilles (Siege Perilous class), and Dylan uses the device again. However, Gabriel has been aware of the device's existence for this whole year ("For an AI, it's an eternity") and has managed to devise a countermeasure. To be fair, though, it would still probably work on any AI not aware of the device's existence.
- Salem: For some reason, after Mercy's snake familiar is exorcised from her, she's now capable of staying in control of herself after Mary Sibley tries to put it back.
- In the British series UFO, the invading aliens use a new superweapon in each attack. It fails not necessarily because it is flawed but also through bad luck. However, they never try it again although it still exists and might be devastating in another attempt.
- In the first season finale of Witchblade, Sara chooses to go back in time to the first episode, thus undoing everything that happened in the series so far. She is specifically informed that this will only be possible to do once, presumably to stop that ability from being a Game-Breaker.
- Supernatural: In season 7, Sam and Dean eventually acquire a Villain-Beating Artifact that can be used to kill an otherwise Nigh Invulnerable Leviathan, but it can only be used once. They decide to target their leader Dick Roman, hoping that his army will collapse without him. When the weapon is finally used, it sucks both Dean and Castiel along with Roman into the monster afterlife.
- Some particularly gutsy BattleBots competitors have chosen to equip their bots with weapons that can only be used once per match:
- Chrome Fly has an otherwise fairly standard design, but it has a companion drone that drops a cylindrical weight. As the drone cannot retrieve this weight and can only carry one at a time, it can only use it once. As luck would have it, the one time it dropped the weight in its entire career, it missed.
- Double Jeopardy has a cannon as its main weapon that shoots a similarly shaped, sized weight, though at about 190 miles per hour (or about 305 kilometers per hour). Like Chrome Fly's drone, it can only shoot it once, as it's not equipped to reload another slug. Unlike Chrome Fly, it managed to hit its opponent Gamma 9 on its initial match, though Gamma 9's operators were never directly in front of Double Jeopardy whenever possible, which meant it didn't fire that cannon until right before it was knocked out.
- In an early episode of Pee-wee's Playhouse involving a thunderstorm, Randy shows Pee-Wee how to prank call someone by calling up a woman on the picture phone and asking "Is your refrigerator running?". When it's Pee-Wee's turn to do a prank call, he calls up the exact same person with the exact same joke. She obviously doesn't fall for it the second time.
- Bryan Danielson ended his best of five series against Homicide to get a shot at the Ring of Honor World Champion with a 100 rotation air plane spin. When he tried to use it again during the title match, Austin Aries slipped out of it after 30 rotations. Danielson's inability to take the title from Aries led to him going into voluntary exile from ROH until he knew he could do it.note
- Most of a PC's powers in 4th Edition Dungeons & Dragons only work once per encounter or once per day. At least they can be recharged between fights, though...
- For arcane or divine spells, this is justified by encounter and daily spells requiring a minute or two or longer of memorization, preparation, and/or prayer to prepare. For physical powers, it's explained that they are so physically demanding or reliant on surprise tactics that your character can only perform (or get away with them) once. This is one of the main reasons why there's a Broken Base over this edition: some players find that it's not airtight, but in most cases it works under Rule of Cool; other players find this a ridiculous case of Fridge Logic.
- The GURPS Player Handbook suggests the DM should reward a clever player who comes up with a new gambit by letting the trick work ... but only once. The example given is throwing sand in an opponent's eyes to blind him — might work once, but if it were really that effective all the time, "fighters would leave their weapons at home and carry bags of sand instead." Thus to keep the game balance, creative gambits should only work once.
- Champions. The villainous robot Mechanon has automated factories around the world. Whenever he's destroyed, one of the factories creates him again, this time with defenses against whatever destroyed him. This makes it much or difficult or even impossible to destroy him the same way again.
- Almost every RPG is open to this trope. The GM probably had a pretty good idea of how you are supposed to get past a bad guy but either hinted at it too subtly, the players were point blank oblivious to anything other than violence or hilariously botched rolls while trying to figure it out, they just don't get there. And that means that the GM either has to murder all the PCs or let them lash together a plan between themselves to leapfrog this particular station on the plot railroad. But only this time.
- Alternatively players being what they are, they may put in WAY more time and effort into working out how to defeat the bad guy from a Rules Lawyer perspective than the GM hoped, and thus arrive at a fait-accompli that is irrefutable from a rules standpoint but not what he had in mind. Given the effort involved, the GM has to let it pass this time, but threats (or possibly rocks) are likely to be passed should they ignore the plot and focus on breaking the system in future.
- In Chuubo's Marvelous Wish-Granting Engine, which has plenty of powers that are very draining if you use them more than once in a chapter or even once in a book, and a few (such as some forms of Reality Syndrome) that simply cannot be used more than once per chapter, the Salvation power from the Wounded Angel arc works once per campaign. It is the only power in the entire corebook with this limitation. To be fair, it's a strong power, enabling you to reshape the world to save someone for whom all is lost, but still!
- In Tales of Symphonia: Dawn of the New World, Emil's Mystic Arte Ain Soph Aur can be used on Richter the first time, but if you try using it again, he will counter it with a Mystic Arte of his own, magnifying its damage output and targeting your entire party.
- The huge cannon you weld to your mining-vessel-turned-mothership in Homeworld Cataclysm has the problem of only working once before requiring major repair. The ship it's attached to is initially civilian, and energy conductors and heatsink systems suitable to power a cannon about a third of its entire size were not included in the original designs. Searching for them is a major plot point taking up several missions - though it does, eventually, give you a cannon whose reload rate doesn't include an inter-mission cinematic.
- In the second chapter of Disgaea, Flonne summons a dragon to attack you, announcing that because she has to use a special item, she can only do it once - thus, after she joins your party, there will be no dragon-summoning.
- This can be partially averted... by capturing the dragon she summons, allowing YOU to summon the dragon whenever you want!
- And then it's entirely averted... In Disgaea 4, where both Archeangel Flonne and Fallen Angel Flonne have it as a move, with the same incantation. The former summons a normal dragon while the latter summons a zombie dragon.
- For a more literal interpretation of this trope, Bonus Boss Pringer X is this trope. Any special attack used against him will only damage him once. If you're fighting multiple Pringers, they all become to immune to the special move.
- The Master Ball, which has a 100% chance of capturing any Pokémon, but often only appears once in each game, which becomes especially frustrating in later generations as the number of stupidly-difficult-to-catch Pokemon increases. Later games have it given out in the lottery, but only if every number matches. So you can get more, it's just really really really rare to.
- There is an item called the Sacred Ash, which revives all fainted Pokémon in your party AND fully restores their HP. The catch, usually the only place it's found is Ho-Oh holding it, so there's only one in the game. The Festival Plaza in Sun & Moon, however, lets you purchase it.
- TMs were initially one-use items and often limited to one per-game, so you only had one opportunity to teach Blizzard to a Pokémon. Pokémon Black and White onwards, however, made them have infinite uses.
- Some TMs could be bought in the first four generations, so the player technically could teach certain TM moves to multiple members of their party. However, the TMs could still only be used once apiece, so players would have to repeatedly buy them to do so.
- There are a few moves like Overheat and Draco Meteor that, while very powerful, cut the user's Special Attack stat in half. Naturally, this means that it should wipe out whatever it attacks, because the Pokémon will be effectively useless for the remainder of its time out of the ball. This can be remedied by recalling it, but as that's the obvious move, the opponent will be able to predict you doing that.
- A more extreme version would be sacrificial moves which cause the user to faint. These range from support (such as the stat-lowering Memento and the healing Lunar Dance) to attacks (such as the high-power Explosion or the damage-equal-to-lost-HP Final Gambit).
- The move Fake Out is a high priority attack that makes the target flinch 100% of the time, but it only works on the first turn the user is sent out.
- The same goes for First Impression, a Bug-Type variant more than twice as strong introduced in Generation VII. Of course, the only Pokémon that can use it is Golisopod...
- Z-Moves can only be used once per battle.
- Burn Up requires the user to be a Fire-type to use, and causes them to stop being Fire-type when used.
- In Star Ocean: The Second Story, Claude uses his phaser beam (which the planet's locals call a "sword of light") to dispose of a beast attacking Rena. When he gets to the second town, he uses the phaser to break down a door, and it promptly (and inconveniently) runs out of power, and can never be used again.
- To some degree this happens in Paper Mario 64 in the first (non-hopeless) fight with Bowser; his invincibility can be canceled out with the Star Beam you've spent the entire game earning. In the second a short time later, the move is now useless and you must get one better to win.
- Command & Conquer series:
- In the original game, NOD only had the capability to launch a single nuke (it was a lot more powerful than nukes in the later C&C games though). GDI's counterpart, the Ion Cannon had no such limitations.
- In the Yuri's Revenge expansion of Red Alert 2, partway through the fourth Allied mission in Egypt you get one free use of the Psychic Dominator after you rescue Einstein from Yuri's clutches - he managed to sabotage it under Yuri's nose before your forces rescue him. He states it is unstable, though, and will self-destruct before you get a second use.
- The call-in supertanks in Company of Heroes for the Axis factions, the King Tiger and the Jagdpanther. You get one per game, and God help you if Allied AT guns knock them out (and you don't have a Bergetiger to revive them). Then again, if the Allied players are still putting up a defense as opposed to screaming like a little girl, there's something wrong...
- In Wing Commander: Prophecy, the protagonists capture an alien plasma weapon capable of destroying a fleet with one shot, install it to their carrier and successfully use it to destroy an enemy blockade. They then determine it would be too dangerous to try recharging it for a second shot.
- Humorously described by one of the characters as "Fire and Forget. We fired it once, now we can forget about ever using it again."
- In the original Metal Gear Solid, feel free to hide in a cardboard box right in front of the enemy. If they see you, they'll look at the box in confusion, then move on. However, if the same enemy sees that same box in the same place, he'll pick it up. Apparently, it's more suspicious for the box to still be there than for it to suddenly disappear.
- In League of Legends, Poppy's ultimate ability, diplomatic immunity can turn out like this. Offensively, she uses it to take down an enemy champ without fear of repercussion from the rest (Unless they crowd control her and force her to waste it.) but once they're gone, she is immediately vulnerable and they'll likely get her down so she doesn't assassinate the rest of the team. However; it's fully possible for her to ult someone else, then wreak havoc without touching them, or declare Diplomatic Immunity in someone else and uses it to escape, which doesn't work just once....
- Or any of the ap nukes, notably Katarina and leblanc, once you use up your whole nuking combo... you can only do small non-damaging auto-attacks. Good thing their cd are short, and katarina have her passive... This is why ap loses their powers late game.
- A better example is the concept of the carry in general which can become this when taken to extremes. If one person on the enemy team noticeably gets lots of kills, the most common counter tactic is to wait for the opportunity for all 5 members of your team to dogpile that champion since they're clearly the biggest threat and need to be eliminated on sight. If they don't properly account for this, then their domination of the early game becomes their one shot, and the rest of the game is it not working since their enemies never let them act freely again.
- In Quest for Glory IV, the ultimate joke is this. Anyone who hears it will laugh, no matter how little a sense of humor they have, but only the first time. You use it to distract the Big Bad long enough for you to kill him.
- In Batman: Arkham City, each of the takedowns against Mr. Freeze only work once, as he'll adapt to them. You must find five unique methods of taking him down. In the higher difficulty modes, you have to figure out even more ways to attack him.
- In the comic book tie-in Batman comes up with the idea of disguising the Bat-boat as a fishing boat to sneak into Arkham City. It works brilliantly...until he tries it a second time, where the boat winds up blown up with a rocket. Lampshaded by Batman.
Batman: That worked a grand total of once.
- In the comic book tie-in Batman comes up with the idea of disguising the Bat-boat as a fishing boat to sneak into Arkham City. It works brilliantly...until he tries it a second time, where the boat winds up blown up with a rocket. Lampshaded by Batman.
- In Resident Evil Outbreak: File #2, you find an Explosive Leash control for the rampaging tyrant, which you can use to skip one fight with him. It doesn't kill him, though, and if you use it early he will return.
- The console-only game (later ported to mobiles) Civilization Revolution only has one nuke in any single game. It's given to the player who builds the Manhattan Project wonder. It can hit any city or square on the map but leaves no fallout. Doesn't stop enemies from declaring war on you at the drop of a hat.
- In Marathon 2, Durandal gets frustrated by this trope. He has a clever plan to introduce a virus into Pfhor war machines and turn them against their masters. It works... for about twenty minutes, before the Pfhor render it ineffective. Turns out another alien race called the Nar had that same idea twenty years ago, and the Pfhor have set up countermeasures against such tactics.
- Chrono Trigger: After completing Robo's Quest and Lucca's Quest, Robo will offer Lucca a piece of Amber, which he'd made by compressing tree sap inside himself during his 400-year wait. The Amber is an Accessory, which grants the Auto-Life/Reraise status. It will work one time, and one time only.
- In Mega Man X3, you have the ability to swap out with Zero. It can only be used once per stage and if he dies, you lose him for the rest of the game. He's also needed to get his saber near the end of the game.
- XCOM: Enemy Unknown
- Rockets. Since the Heavy Class is carrying a light machine gun (the heaviest weapon in the game), he is already very burdened, so he can only carry one rocket, with no way to resupply during a battle. Well, technically, if he takes the right promotion perks, he can use two rockets and a special shredder rocket (which causes less damage but inflict a Damage-Increasing Debuff), still, with a maximum of three rockets, make them count.
- All active items work similarly. The medikit gets one use (three with a Field Medic Support), four when he gets Deep Pocket in Enemy Within), grenades can only be used once (twice with the Grenadier Perk from the Heavy, or the Deep Pocket support ability in Enemy Within), the Arc Thrower can only be used twice (thrice with the Support ability Deep Pockets), the support Smoke Grenade can only be used once, twice with the Smoke And Mirrors ability (thrice in Enemy Within). It had to be noted it applies only during missions, as the squad gets resupplied for free between missions.
- In XCOM: Enemy Within, there is a scripted event involving an alien attack on your base (if you lose this mission, it's Nonstandard Game Over for you). The means the aliens use to Mind Control on some of your techs to get them to sabotage your base defenses is stated to be a one-off.
- The final boss of Undertale's Neutral Route empowers himself by absorbing the six human souls the monsters had collected by that point. As the battle progresses, you call for aid and the souls answer, rebelling against the one using them and eventually enabling you to win. This character also possesses a Ripple Effect-Proof Memory of your gameplay, so on subsequent playthroughs, if you reach the Neutral route's final boss again he'll opt not to go through with it since he knows the souls will simply revolt against him again and the end result will be the same.
- Owing to a programming error, the Dragon Zombie of Final Fantasy VII will cast its ultimate spell "Pandora's Box" at you only once - after that, no enemy will ever attempt the spell on you again (unless you start the game over). Your party can learn the attack for themselves, but if you didn't have an Enemy Skill material on them at the time, it's gone for good.
- We Happy Few: When a person remembers the past and refuses to take their Joy for long enough, they become a "downer"; in other words, they're a perfectly normal person in a world gone insane. Joy no long has quite the same intoxicating effects for them as it once did. It wears off very quickly, and leaves the individual extremely depressed, hungry and thirsty.
- Fate/stay night: A problem when facing Servant Berserker. He's incredibly powerful, so to manage to damage him at all is quite an effort... but he has the God Hand Noble Phantasm, which allows him to revive himself 11 times, so you'll have to kill him twelve times to finally finish him off. Worse, he becomes immune to whatever it was that killed him last time, so you have to do it twelve different ways. Of course, there's nothing saying a sufficiently powerful attack can't take away more than one of his lives at once.
- Gems of War: One-Shot * spells, which can only be used once per battle.
- The Legend of Zelda: Breath of the Wild:
- In the past, the Divine Beasts and Guardians were instrumental in the defeat of Calamity Ganon, so much so that King Rhoam insisted on using them again and following the same plan to the letter when Ganon inevitably returned. Unfortunately, he failed to consider the possibility that Ganon would remember how he was defeated last time and change tactics accordingly... by corrupting the Divine Beasts and Guardians and turning them against Hyrule.
- During the fight with Maz Koshia at the end of "The Champions' Ballad" DLC, Link can use some Mighty Bananas as a Delicious Distraction, though the boss will only fall for it once per fight.
- In Sheep, Dog 'n' Wolf, Ralph Wolf uses a magic flute to hypnotize Sam Sheepdog and lure him away from the flock of sheep. It works so well, it's available to use in the next level. However, it's revealed that it won't work anymore as Sam now has earplugs.
- Fate/Grand Order: In her original life, Queen Medb from Celtic Mythology was assassinated by having a hunk of cheese hurled at her with a slingshot while she was bathing. During the Summer 2017 event, the heroes attempt to have Enkidu hurl a hunk of cheese at her while she is taking a shower. She deflects it and says she's developed a Spider-Sense for cheese.
- In Persona 5, the Phantom Thieves force a change of heart onto corrupt people by stealing the manifestation of their distorted desires, their "Treasure", from that person's Palace. To make the Treasure take physical form, the Thieves have to send their target a Calling Card in the real world to alert the target that they will steal their desires. The shock and paranoia from the warning are what makes the Treasure physical. The drawback is that the initial shock of the threat will eventually wear off and can never be recreated, meaning that the Phantom Thieves only have a short window of time to steal the Treasure and only get one shot at it.
- Silent Hill 3: The Seal of Metatron from the first game. Granted, Alessa knew how to use it (having been Dahlia's daughter and all), and she only sought to contain "God" and the Otherworld within her area. Alessa's next incarnation though she may be, Heather is ignorant on how it works; and it is reportedly "difficult to control," indeed making it "just a piece of junk"...in her hands. Presumably Vincent doesn't know either, seeing as he would've told her how to use it otherwise. Leonard was only appointed its guardian, expecting a member of "the order" to be the chosen one to use it, so it's also doubtful that he knew how to use it. Claudia may or may not have known the required ritual, but denies its efficacy. Oh, well...at least Harry left Heather a little present.
- In Cwen's Quest mysterious life slave Riddly Lancer defeats a huge dragon with an equally huge DBZ style blast. Next chapter when asked to do it again against to defeat the next bad guy he simply reports he can't do it again. Luckily he apparently has a few other skills.
- In The Order of the Stick, Vaarsuvius makes a deal with a trio of demons to become a virtual God-Mode Sue, but later claims that it can never be done again. This is probably true, since the demons have no reason to help now, but it is likely the real reason is trauma: while in power Vaarsuvius not only did some really nasty things, but nearly got killed due to overconfidence.
- We don't know if they didn't have any reason not to help hir, another is the other end of the deal which is giving the third-party villains time for which Vaarsuvius must serve them.
- V wasn't saying the deal couldn't be made again, but was saying those spells couldn't be cast again. And they couldn't, since by that time the deal was finished, and Vaarsuvius didn't have the three spirits shackled to allow it anymore. Since they had been level drained repeatedly by then, it's possible the spells would be lost anyway.
- In chapter three of The Adventures of Dr. McNinja, Dan McNinja defeats Frans Rayner by punching him in the right butt cheek and exposing his neckbeard. Years later, when Dr. McNinja fights him, Frans has moved his weak spot to a different location and taken extreme precautions to keep his beard from ever being noticeable.
- Also applies to holy weapons throughout the series: it's one banishment per weapon, and if the numbers suddenly change on you, you'd better have another trick up your sleeve.
- The Treasure Juju in Homestuck can only ever be used twice, but each use is so drastically different that they could technically be different items. The first time, it can only be used by Caliborn as a weapon against his enemies (by sealing them away inside it forever). The second time, it can only be used by Caliborn's enemies against him (by unleashing their power in one concentrated blast).
- An explicit theme of Fine Structure. Any given superscience technique will only work briefly before the Imprisoning God notices and changes the physical laws of the Universe to make it impossible.
- Leet, a Gadgeteer Genius in Worm, has this as an explicit part of his superpower. He can invent a machine to fulfill any function...once. The second time it just explodes.
- Crawler, a cape with an adaptive healing factor, becomes resistant and eventually immune to any form of damage he sustains and from which he regenerates.
- Draugr, from The Saints, like other undead, have specific weaknesses. Unlike other undead, the quickly adapt and overcome those weaknesses.
- According to Things Mr. Welch Is No Longer Allowed to Do in an RPG, sending a stripper to the guard office follows this principle.
- Whateley Universe: A few devises work like that. The Psi-grenade, cannot be recharged after its been detonated and Mega-Death's Force Field Disruptor burns itself out after its been used. But multiples of each can be made.
- In the Counter Monkey episode "The Bardic Knock Spell", Spoony discusses this in relation to RPGs, saying that if you can impress the Game Master, he'll let you get away with doing something really audacious, but he'll only give it to you once. The example he gives, the titular "spell", involves gaining access to the villains' stronghold by just knocking on the front door, then punching out whomever answers.
- A more straightforward Looney Tunes example would be the Bugs Bunny / Daffy Duck cartoon "Show Biz Bugs" in which he is trying to go one-up on Bugs in their stage act. When none of his tricks impress the audience, he desperately tries his ultimate trick: downing several kinds of volatile explosives and then swallowing a lit match ("Girls...better hold onto your boyfriends!"). The trope title is obviously the punchline to this gag. The same gag was also used in "Curtain Razor" with a wolf trying to impress Porky Pig (which is a talent impresario in this short) with his act. In the end, the wolf gets his chance after several attempts, then doing the trick aforementioned, and as expected, the same punchline (kinda) is delivered.
- The Kim Possible episode "Queen Bebe" and The Powerpuff Girls episode "The Boys Are Back In Town" both have the heroines confronting a previously-defeated opponent and trying what they used last time, only to find that it doesn't work anymore.
- Subverted in Family Guy. Peter and Brian get rid of James Woods by leading him along with pieces of candy and trapping him in a crate. When he comes back later, he steals Peter's identity and they go through a long ordeal, but then Peter and Brian eventually get rid of him in the exact same way with Peter pointing out that they should have tried this again from the beginning.
Peter: Okay, Brian, next time let's remember this right away because he's done this twice.
- Subverted in The Simpsons where they try to get Maggie out of a locked bathroom. Homer tries a coat hanger then gives up. Lisa tries it again and successfully unlocks the door.
- Both used and subverted in The Batman episode "Meltdown". Batman first defeats Clayface by throwing a freeze-bomb at him. When he tries it later, Clayface said he saw it coming and just made his body hard so it bounced off. Then Detective Yin does this after pretending she was going to shoot him which prompted the line:
Clayface: Didn't expect that from you Yin. I guess you do have... a new partner.
- Something similar happens in Batman Beyond. Inque was vulnerable to freezing and water in her first appearance, but in later appearances learned to curl herself into a ball, protecting the bulk of her mass from being frozen and breaking free in short order, or modifying her chemical makeup to resist water. Batman himself uses this against Inque, protecting himself from being enveloped by her with an electricity based contact defenses.
- The Spectacular Spider-Man: In the Villain Team-Up episode, Doc Ock explicitly points out that none of the methods Spider-Man used to stop his foes last time will work: Doc Ock's arms are powered by Electro, the power pack on Vulture's back is better armored, Electro has much better control of his power (such that he can safely contact water), Shocker and Rhino know better than to confront him in an enclosed space, and um...there aren't any concrete mixers around. It goes both ways, though, since Spidey's also been upgraded since the last time he fought them.
- Superman: The Animated Series saw the Man of Steel use this trope frequently. When his foes escaped from Cardboard Prison, they'd usually find Superman wearing a suit designed to be proof against their powers. Somewhat subverted, though, in that these suits were not foolproof and the villains found ways around them (or just ripped them off).
- Mojo Jojo tries to avert this in an episode of The Powerpuff Girls by trying an old plan a second time, thinking he's taken precautions against what ruined the plan the first time. The girls defeat him anyway, showing that maybe it's best to turn your back on plans that have already failed once after all. Considering that his precaution was to not turn the girls into dogs, thus preventing them from biting his butt (now protected by a metal plate, one would think that doing either of those things cancels out the usefulness of doing the other, but whatever) and making him break the magic idol he was using, they weren't very good precautions. He forgot that, since the girls aren't transformed, they can foil his plans in the same way they foil all his plans; by beating him up.
- Justice League Unlimited:
Flash: (To J'ohn) What's the big problem? Can't you just whip up another batch of that nerve gas?
- After The Flash defeated Brainthor by tapping into the Speed Force, he said he didn't think he'd come back if he went that fast again. Notably, when another version of the Flash in the comics did something similar, he didn't come back.
- Doomsday's Justice League incarnation had the same abilities as his mainstream self.
- Amazo was able to adapt so that the kryptonite didn't work on him.
- Shadow Thief was weak against bright lights in his first appearance. In his second appearance, he comments light hasn't worked on him in months.
- This was actually used in the pilot of Justice League, when Flash asks Martian Manhunter why he doesn't use the nerve gas he used to defeat the Imperium before:
J'ohn: Unfortunately, no. The gas can only be made from a rare Martian plant. I brought a sample with me, but it was destroyed when I was captured.
Flash: Uh, what's Plan B?
- On an episode of The Adventures of Jimmy Neutron: Boy Genius, the title character builds nanobots in a flying saucer to defend him from bullies. They malfunction and begin to threaten everyone who comes within 5 feet of him. He defeats them Logic Bomb style by beating himself up. Take 2: Jimmy re-hires the Nanobots as Beta Readers for his homework assignments, and they take their "correcting errors" to extremes, going so far as to start correcting human error (bad posture, fashion, etc.) He tries to Logic Bomb them again by saying that flaws indicate that humans are functioning perfectly, but they stop trying to puzzle it out, call it "extreme error" and just start deleting people off the face of the earth. Somewhat subverted, though, in that he still uses their programming to overload them; he purposefully miscalculates a number on his homework, and asks the nanobots to correct it. The number in question? Pi, which no computer could calculate to perfection.
- In Titan Maximum, Palmer believes that his favorite move, the Sucker Punch works every time. However his brother Billy, points out that attack can only work once in each fight because it is quite impossible to catch the guy off guard again.
- A Gumby cartoon had Gumby returning a wand to a magician who left it behind at Gumby's lemonade stand (it made sense then). The magician rewards Gumby with a wand that will perform a single trick. Gumby uses it to repair his mother's pitcher that got broken at the start of the cartoon.
- The Lich from Adventure Time is a master of this. If its beaten him once, he'll make sure the heroes don't get a chance to use it again. First off by destroying Billy's Gauntlet before Finn can use it against him. Followed by swatting Finn away while possessing Princess Bubblegum before he can use his "Like-Like Sweater" to destroy him. And as of the season 4 finale, killing Billy, the one who imprisoned him in amber. Notably, it's not because he gets stronger in-between attempts, he's just really good at planning and manipulation.
- John Dread from Max Steel pulls this one on Max. The first time around when Max tricked Dread into punching his claw into magma it was quickly melted off and he was defeated. The second time it happens, Dread lampshades that he fell for the same trick twice, but this time around his claw is made of an alloy that won't melt at that temperature. Cue Oh, Crap! face from Max as he's now facing Dread with a red hot glowing claw.
Dread: Same old trick. Too bad it's not the same old claw.
- In Samurai Jack, Aku manages to fool Jack by transforming into a beautiful woman named Ikra and feeding him a sob story to gain his trust, which results in Aku trashing a portal to the past and taunting Jack about it. The second time Aku tries this trick, however (this time as a Yoda-ish old master), Jack immediately sees through it: he Bluffs The Imposter, turns the plan against Aku, and nearly takes him out once and for all.
- In the Teen Titans episode "Titans East Part 2", Cyborg is the only Titan left who can resist Brother Blood's Mind Control. Blood has effortlessly torn Cyborg's limbs off, paralyzed the other Titans, and is ripping Cyborg's circuitry apart, trying to find the component that makes Cyborg immune. Cyborg announces "It's my SPIRIT!", instantly rebuilds himself, ignores Blood's energy blasts (the ones that blew his limbs off 15 seconds ago) and takes Blood out with one punch. They at least lampshade it this time.
Beast Boy: So are you, like, magic now?
Cyborg: Pretty sure that was a one-time deal. Blood was trying so hard to hack into my brain, I guess I sorta hacked into his.
- In The Adventures of Puss in Boots, this is how all magical fountains work. You can only benefit from the effects of a fountain once, and if you say "release" to negate the effects, you don't get a second chance.
- The Kairosect from Trollhunters is an artifact that allows its user to step outside of time, and while it actually only works three times, Blinky wastes the first two uses demonstrating it.
- The Quantum Destabilizer gun from Gravity Falls zig-zags this trope. Dipper and Ford try to use this against Bill Cipher in Weirdmageddon Part 1. Ford directly acknowledges that they only have one shot, and while the shot does damage Bill, it fails to kill him. Ford is captured, and the weapon is never able to be used again.
- The Elements of Harmony in My Little Pony: Friendship Is Magic against Discord. This time they're dangling the elements over his head as leverage to force him to play along while they try and reform him, but the first two things Discord does is destroy all of Twilight Sparkle's "reform spells" and sweet-talk Fluttershy into promising to never use her element against him, rendering the rest completely useless.
- In an episode of Hot Wheels Battle Force 5, the team needs to head to a nanotech stabilizer and can't afford to go through a Battle Zone first, so Saige reveals a crystal that lets them skip the Battle Zone and go straight to their destination. When asked why they don't always use such a crystal, she reveals that she only managed to obtain one, thus limiting its use.
- One episode of SpongeBob SquarePants has a very picky customer invoke an Achilles in His Tent by making SpongeBob doubt his skills as a fry cook by claiming he forgot the pickles. When SpongeBob returns and confronts him again, he pulls the same trick, but SpongeBob quickly realizes how he got away with it when he starts laughing.
- Early firearms (prior to the mid-18th century or so) worked like this in ground battles. Sure, you could reload them... but it took so darned long (1-3 minutes) and the ranges of the weapons were so short (50-100 yards) that you'd be lucky to get off two (somewhat inaccurate) shots in the time it took for an enemy (on foot) to come within range, charge and attack you with something sharp and/or pointy. Bayonets were developed so that muskets could double as melee weapons, eliminating the need for pikemen. Contemporary hand grenades (thus Grenadier units) and rockets - like those used in China - only worked once.
- Still musketeers and other gunmen usually carried somewhere between 8 and 16 reloads on their person (their flasks with gunpowder were known as "12 apostles", despite there not always being 12 of them). On top of this, there would be carts with more powder and bullets behind the lines. While some generals really liked charging to within range, having to run through the salvos of bullets usually meant the charging formation was in worse shape than the one being attacked by the time they arrived, and stood a big chance of losing the subsequent "push of pike". So it was more common to try and destabilize the enemy formation by firing at them yourselves and by sending loose skirmishers, cavalry charges and cannon fire at them, before actually going in for the melee. So most of the time, this trope was averted. There is a reason these firearms were used. Still, a rush could succeed if performed so fast that the enemy had no time to get ready for the hand to hand. This tactic saw a short period in the limelight after the invention of the plug bayonet, which had to be plugged into the barrel of the gun, and could therefore not be mounted before going into battle.
- The Liberator handgun. It was possible to reload them, it just took a long time. They were nearly useless as weapons, the lack of rifling meant that the bullets would sometimes strike sideways and bounce off of people if fired from more than a few feet away. The were good for super-short range kills, though — if the attacker could get within a couple feet they could be effective. The general idea was to use it to take out an occupying soldier and take his gun. And more importantly from the Allied perspective, to demoralize the enemy with the fact that they have no idea just how many are out there, and how many of the seemingly helpless civilians in conquered nations are actually armed.
- The same applies to The Vietnam War-era replacement, the Deer gun, though its effectiveness as a weapon was never determined; when the war escalated, plans to hand the gun out to civilians in the same manner as the Liberator were abandoned.
- The "Punch Gun", made famous in Inglourious Basterds, is a real gun that only works once in concept. Because you have to hit your opponent to "pull" the trigger, it would be hard to not kill him. But if he has buddies around, you will be in for a rough time.
- The tactics the 9/11 hijackers used to seize control of the planes fall into this category, even if you're not counting increased paranoia around airports making it unlikely that any repeat performances would even make it to the plane (several of the hijackers had been flagged as suspicious, but lax security meant they got through anyway). Generally speaking, since most passengers in previously hijacked airliners did in fact survive, there was no reason for passengers and crew not to cooperate.note Now that using the plane as a kamikaze weapon has been firmly established as a possibility, trying to take over a plane with knives will likely not work because the passengers and crew will fight back and overpower the hijackers. In fact it is a commonly cited theory that the passengers of United Flight 93 knew what had happened to the other flights hijacked that day and either risked their lives because they had nothing left to lose or went on an outright suicide mission to subvert the attackers.
- The M72 Light Anti-tank Weapon, its modern successor the AT-4 and various similar designs based on the same concept. Though arguably they're a subversion, as theoretically they provide the reverse effect in practice; instead of having a dedicated RPG fireteam, who have to spend precious seconds reloading after taking a shot and can't carry a hell of a lot else besides the launch tube and its ammunition, every man in the squad can carry a one-use launcher as part of their regular gear. If one of them misses, another steps up and takes their own shot.
- Successful suicide bombing.
- Likewise, if you botch the bombing such that you don't die but the target knows your intentions, they'll likely try their damnedest to kill you.
- The Trojan Horse gambit - anyone with even the most cursory knowledge of military history will know better than to fall for it. It even spawned the phrase "beware Greeks bearing gifts".
- One of the poetic metaphors for a woman's maidenhead (or, more generally, virginity) is, "the rose that can be given only once".
- Considering what we know now about the hymen (i.e. it can regrow or even not break during intercourse), this is not necessarily the case.
- Medical examples:
- The arsenical medicine melarsoprol, used against African sleeping sickness, is extremely toxic. So toxic in fact, that it can't be administered to someone who's been dosed.
- The precordial thump is a sharp punch to the sternum sometimes attempted during CPR, as a form of mechanical defibrillation in the event you don't have an AED. In real life, it's never done more than once. The thump has to be performed within 60 seconds of the onset of symptoms, making it useless in all but immediately witnessed arrest. (In fact, according to one study, all reported successes have been within ten seconds!) Basic CPR training no longer includes it at all, and Advanced Cardiac Life Support only mentions it in passing.
- Cats do not have antibodies for dog blood cells, so if no feline blood is available, an injured cat can receive canine blood instead. However, within four days the cat will have developed said antibodies and can never receive dog blood again without suffering a severe (likely fatal) reaction.
- Some diseases only affect each person once, since the next time they get infected the body already knows how to deal with the problem. In fact, this is the idea behind vaccines: get infected with a harmless version of a microbe so your body is ready when you have to face the real one. But this also works the other way, since some diseases evolve too quickly for immunity to last very long. This is why new flu shots are issued each year to keep up with new strains.
- Ceramic trauma plates for body armor can work this way. When struck with significant energy (by a bullet, hammer, fragment, splinter or by being dropped), it will crack and the effectiveness of the plate degrades, but isn't automatically rendered useless. However, a second hit in the same general area will typically go through, making this trope true for hits in the same location. With luck, subsequent hits will be far enough away from the damaged areas to be stopped as well. This won't work forever, but has been seen in the field.note Though heavier, the ballistic value of ceramic plates is generally much higher than traditional metal trauma plates.
- This is also the case behind Explosive Reactive Armor (ERA) for tanks and armored personnel vehicles. When touched by an EFP (Explosively-Formed Projectile, the most common form of anti-armor round in use today, which essentially is a bolt of molten metal), the ERA plate explodes, disrupting the jet and preventing it from penetrating the vehicle's armor. Once an ERA plate detonates, that section is unprotected from further hits until it is replaced. While it's very hard to hit the same spot twice, especially from far away, it's not impossible. ERA-protected vehicles have been destroyed by such unlucky double strikes. Newer armor-defeat munitions actually stack multiple shape-charge warheads that fire in sequence, burning through ERA and armor and allowing the hindmost EFP to penetrate to do damage.
- Before the release of Fallout 4, an excited fan sent Bethesda a box of real-life bottle caps weighing over 11 pounds with a tongue-in-cheek letter asking Bethesda if this would be an acceptable substitute for payment. To his surprise, Bethesda then sent him an email accepting the "payment", and agreeing to send him a copy with the understanding that it'll only work the once.
- A "zero-day" vulnerability is a computer security hole that is not yet generally known, named for the fact that nobody has had time to develop defenses "zero days" after someone discovers and exploits the vulnerability. Once a zero-day exploit is used and noticed, cybersecurity experts will study it and develop countermeasures to be distributed in future security patches.
- In Sports, particularly American Football, trick plays tend to fall in one of three categories: Either they're so genius, they become part of the game, or they work based on being illogical and not what the opponent would expect (in which case they will remain rare and often only used in desperate situations) and the third category are those that make use of Loophole Abuse, in which case there is likely to be an Obvious Rule Patch right after it's been used the first time. The first category is often not even considered a "trick" any more and includes stuff like play action passes, the second includes stuff like fake punts and the third includes stuff that is usually subject to quite a bit of controversy afterwards, such as the "Holy Roller" play or the shenanigans the Patriots pulled with declaring different receivers ineligible in their playoffs matchup against the Ravens some time in the 2010s.