In a game where most classes had roughly 300 HP at max level, the Medic's Immunize was the difference between most enemies hitting for 250 and for 25. Sadly, Heroes of Lagaardcut it out altogether (along with the Troubadour's Healing and Relaxing skills)
Immunize in the original game was broken due to a bug with how it handles elements. Normally, it should only affect Elemental Resistances, but for some reason, the physical damage types were treated as Elemental as well, and thus you have a powerful damage reduction buff, that when combined with the Protector's Defensive Formation and Elemental immunity shielding techs, allowed you to only take minimum damage during the final boss.
Once you get to the 5th Stratum, money is no longer a problem, as just close by the Warp pole is a mining point that can be mined without fear of being attacked and making thousands of En per run with a team of Survivalists with maxed out mining. Like with Immunize, future games nerfed the gathering skills to prevent this from happening again.
Heroes of Lagaard
When the developers were rebalancing things for HoL, they boosted some previously-useless skills - a bit too much, in some cases.
The Hexer skill Revenge was boosted to deal 255% of the damage the Hexer had taken for only 19 TP once mastered, which means a Hexer with items to boost max HP, 1 HP left, and enough AGI to move first can be devastating.
To elaborate: Revenge deals set damage depending on how much HP a Hexer has lost, ignoring enemy's defense, resistance, immunity, etc.; if a hexer can deal 1000 damage to a mook, they can deal that much damage to a Boss. In Heroes of Lagaard, not only was Revenge's strength buffed, the HP of FOEs and bosses were nerfed. In HoL, the highest HP among non-Final Boss or Bonus Boss is around 3000-4000, but said bosses have a massive amount of defense. With proper equipments and setup, Hexers can dish out between 1500 to 2000 damage per Revenge. A Boss Fight using other classes can last 10 turns or even longer, while Hexers can happily wipe out a boss in possibly two hits.
While not as conveninent, a Hexer with Evil Eye and Suicide can command the enemy to attack itself instead of the party, allowing the player to attack an enemy without worry of being hit. There's also Betrayal, which forces all terrified enemies to attack each other. Adding in Relapse, it's possible to cripple an enemy for the rest of the battle.
The Dark Hunter's Climax was similarly buffed up. Once mastered, it kills any enemy vulnerable to instant death with less than 55% of its HP (previously, it only had a 20% chance of working, even when mastered). Most bosses are immune to Climax, but F.O.E.s aren't; having Climax mastered essentially halves the duration of any F.O.E. encounter.
A War Magus' Cursecut can drain TP from an enemy that's been cursed (best done with a Hexer, which, as mentioned above, is a Game Breaker in and of itself). War Magi can also transfer their TP to other characters by the use of their Transfer skill. With this combo, you have potentially limitless TP. A shame that this is pretty much all that a War Magus is good for...
In addition, the Hexer's Torpor immensely aids the War Magus' Sleep Cut, allowing the party to deal pretty massive damage while the enemies are asleep.
Force skills in general could be fairly severe Game Breakers. The Gunner's guarantees that you'll stun an enemy for that turn and the Protector's negates all damage and status effects for one turn, for example. The Dark Hunter's is guaranteed to go last in the turn, but will bind any enemy, including bosses, preventing them from using their skills (though some exceptions exist). That enemy can waste a turn trying to use a skill that requires the bound limb. At the end of the game, it's possible to use them every turn by dedicating two characters to feeding the Force skill users Axcelas. However, not only do they cost a lot, but also require plenty of materials in order to buy them.
Dampen, which is another Hexer skill, applies a debuff that neutralizes the target's resistances and immunities the moment a single point is invested in it. Depending on the target or the party build, applying this can pretty much double your party's damage output. Further investment will begin to force the target to take increased damage from everything they're not already weak to. The drawbacks are that it doesn't stack with Frailty, a stronger defense debuff for amplifying neutral hits, has a terrible speed modifier, and certain bosses react adversely to its effects, but other than that it becomes very handy in attaining conditional drops.
The Drowned City
The infamous Warrior's Might team, which uses a Gladiator/Shogun and two Shogun/Buccaneers. The Gladiator's class ability and self-buff skills give it some of the highest damage output in the game, and its Shogun subclass lets it use Warrior's Might, a chaser skill that makes it follow up every party member's attack with one of its own. This would normally be balanced by the party limit of five (six with a Ninja's Bunshin), especially since some members will be too busy healing, guarding other members, or maintaining buffs to attack. However, the Shoguns' class ability, Second Sword, lets them dual wield weapons, and their Buccaneer subclass gives them Swashbuckling, which lets them attack 2-4 times per weapon when using normal attacks—and Warrior's Might treats every single normal attack as a separate attack. Throw in a bunch of offensive buffs and defensive debuffs from your other party members, and you can perform 8-16 chase attacks to inflict as much as 40,000 HP of damage on the final boss in one turn.
The Ninja/Zodiac TP battery. The Ninja's class ability, Keburi no Sue, cuts its skill TP requirements by up to 9 points. Subclass to Zodiac and you can use the Dark Ether skill to allow a row of characters to use skills at no TP cost—this would normally cost 10 TP, but with Keburi no Sue, this goes down to the minimum of 1 TP. Now you can spam your party's strongest skills constantly at a cost of just 1 TP per turn. Want to have a pair of Zodiacs nuke the enemy with 60 TP Meteors every turn? Want your Gladiator to use the above Warrior's Might combo every random battle? Now you can!
Legends of the Titan
The Dancer's bottommost dancing skills - Fan Dance, Sword Dance, and Mist Dance. These passive skills give an increased dodge chance, the ability to hit multiple times in a single attack, and the chance to stun an enemy upon connecting with a normal attack. It only takes three skill points to unlock Sword Dance, compared to the sixteen (at least eight of which are dumped in a useless skill regardless of what weapon you use) it took to unlock its predecessor Swashbuckling in The Drowned City. Dancers are also able to use a different skill to make allies in the same line follow up on their attacks, meaning it's possible to have your entire front line attack multiple times per turn.
Want to crank the fun Up to Eleven? Give them the Nightseeker subclass and make them Dual Wield. The multiple attacking can trigger both weapons individually. If you have Sword Dance maxed, your Dancer can potentially attack eight times per turn. By the way, did we mention that the Dancer is both a buffer and healer?
Flip it around and it's still very potent. The maximum number of hits are not as high due to the lower skill point cap on Sword Dance, but each secondary hit can do more damage due to the higher Blade Flurry cap. If the primary weapon can also inflict ailments on normal attacks, all the better, as the Nightseeker passives will proceed to at least double the damage of all subsequent hits once an ailment lands!
The secret class Imperials in Legends of the Titan count as well. They're restricted to using only one type of weapon (they can't equip a subweapon alongside their class-specific weapon) but are capable of dealing thousands of damage without attack buffs. To balance the class, they're given a few cooldown turns until they're allowed to use it again. However, they can use two skills to cool down their weapon (which deals damage as well) and then use an attack that charges up their next turn's attack power (which more than doubles their power even without the skill maxed), which happens to be the same turn they're allowed to use the powerful skills again. If an enemy somehow manages to survive a few of those attacks, there's even a skill that removes the cooldown time for three turns and immediately cools down their weapon after a certain amount of overheats occur in a battle, allowing the character to deal massive damage without any drawback for three turns.
Want to jack up the damage even more? Give them a Runemaster subclass. Elemental Runes can actually create weaknesses in enemies that otherwise take neutral damage, and Runic Flare raises damage when you strike a weakness. The result: an incredibly powerful elemental Drive attack.
Once a Nightseeker hits high enough level to be able to use Venom Throw, maxing it out allows them to inflict a poison status that does a fixed 700 damage every turn for several turns, enough to make a large dent in even most bosses' HP. Combine this with Spread Throw and Auto-Spread which allows them to hit every enemy with the next 2 throw skills and a chance to use said skill for free at the beginning of the battle, and they can take out most random encounters in a single turn with very little TP used. If you then give them Arcanist as a subclass, you can not only use one of their passive abilities to increase the chance of landing the poison status on even strongest enemies, but also gain back any TP you spend to use the move if the poison sticks on at least a single enemy thanks to their TP Return.
The offensive passives given by the Bushi make them a staple subclass for anyone focused on dealing damage, seeing that these skills give a massive bonus with minimal skill point investment. With a single point, their Blood Surge gives a long-lasting buff that doesn't consume a buff slot, drains miniscule amounts of HP and TP per turn, and gives a 45% damage bonus. And that's before we factor in Charge, Defiance or their own Power Boost. Never mind the Bushi's own attack skills - imagine all these damage multipliers stacked on an Imperial!
The Sniper's Squall Volley. This attack at max level can hit anywhere from 6-16 times, with low accuracy. However, if an enemy is inflicted with the Paralyze, Blind, or Panic Status, or has their legs bound, their evasion rate basically turns off. Snipers have easy access to leg bind with their natural skill set, along with the ability to inflict critical hits and raised critical chance against enemies with binds. What this amounts to is a ridiculous number of hits on the enemy, at least half of them being criticals. Oh, and all this can proc more follow-ups with a Landsknecht's Link skills.
The Millennium Girl
Hexers break the game again with Stoning Curse, an extremely reliable petrification spell (which instantly kills the target) against normal enemies with a low TP cost. Unless there's a massive group of enemies that require Evil Eye, Stoning Curse is all a Hexer needs to use outside of F.O.E. fights and boss battles.
Speaking of Evil Eye, it got buffed from its previous incarnations. Instead of just targeting one enemy at a time, it targets a row of them. Curses increasing ailment chance make it more reliable as well, so Hexers become even more powerful than they were before.
Dark Hunter is, for the most part bar none the strongest offensive class in the game.
Viper covers their early game. At level 10, and boosted, almost everything is vulnerable to the poison effect, and its easy to apply to anything, even bosses, and it does absurd damage due to its insane multiplier, almost dealing 4 digits of damage when the other potential party member struggles to be half as powerful. And due to Good Bad Bug, Viper could bypass Golem's self reviving effect, significantly reducing the duration of the fight.
Ecstasy, the Signature Move of the Whip skillset is obscenely effective. At level 10, an Ecstasy with no bound parts is just as powerful as 1 bound parts, and it just become much stronger with 2 or 3 bound parts. Used alone, Ecstasy is already one of the most powerful physical offensive skill in the game. At its maximum potential, its far and away the strongest offensive skill in the game with the possible exception of Land Slash.
Wrath Might increases your offensive power by 40% whenever the Dark Hunter is low on HP and this can be stacked further with the Grimoire mechanic. All of this combined result in Dark Hunter being by far the strongest damage dealer in early, mid, and late game.
The Gunner skill Action Boost. It allows you to take any action twice (three times if you level it up enough) for your next turn, but Action Boosted skills still require TP for each use. The game breaker is, provided the skill that triggers it is increased by Boost, all attacks in that chain are boosted. This allows you to fire off multiple powerful, Boosted skills (such as Ricochet) without any drawback, as long as you have enough TP. With some manipulation, you can easily get Ricky buffed, then have her unload multiple successive skills at once.
Mastery of the Grimoire system (most likely via the item duplication glitch to spam Hunting Horns) will significantly augment any party's power. For instance, spreading the Alchemist's Formula Mastery around can boost elemental damage for other members of the party. Most notable use? Giving the above-mentioned Action Boost to all your offensive party members.
Its also possible to essentially double the power of most passive skills in the game with the Grimoire System. Simply put a skill that a class have naturally, and if they learned the skill, the game will increase the benefit by multiplying the highest level between Grimoire and Naturally learned skill by twice. This is mostly notable for Mastery Skills, since every mastery, except for Sword is able to be stacked, resulting in a significant increase in offensive power.
A number of the King Grimoire skills (Grimoires dropped from certain bosses, with unique skills). The most obvious is Phoenix Wings from Iwaoropenelep, which allows the entire party to move before all enemies; combined with stuns or other status effects, it can lock down enemies before they can even attack. Wolf Pack from Fenrir is also great, giving a massive damage boost on the turn it's used. The only counterbalancing factor is the sheer luck or effort needed to attain these skills due to the process being a Guide Dang It, but when you get one, its power can trivialize most of the game.
With proper knowledge of the mechanic, and a little bit of luck, it is possible to get a number of skills from bosses that would significantly reduce the difficult parts of the game, such as random encounters. Some notable examples are Hurricane Punch, and Flood for early parts of the game, and Burning Ray, and Tendril Thrash for late game. Post game have the extremely powerful Elemental Torrents as well. The catch about these moves are, by knowing how the boss pattern works, you can consistently get them on your grimoire at an acceptable level.
The Fafnir Knight
The cafe option added to the game in terms of money grinding. Tired of waiting for your spoils as you keep doing stuff at the labyrinth? Go find a room with no encounters, place an auto-walk path, and leave it there for 12 hours or so. Your money earnings will amass quickly.
Want to generate vast amounts of experience? The Strong Clover Tea, brewed from one of the Yggdra Bud rare drops, not only triples your experience gain, but allows for experience gain for your other Guild members not in the active formation. And yes, this multiplier is also applied to experience gained from completing story missions and sidequests.
The titular hero of Story himself, due to his transformations. It's saying something when a common complaint about him is that he's so powerful that the other party members are completely overshadowed in the offense department that they aren't even needed as attackers at all. And if that doesn't explain how powerful he is, he can kill the Bonus Boss in one turn.
Accelerate is a charge skill that gives the transformed Fafnir the ability to fire off three attacks in rapid succession the next turn. There are many, many ways to exploit this to ruin your enemies with ease, and is the sole reason why the Fafnir is so strong. While you can only use this skill once per Transformation session, if you use Force Reset to cancel your transformation and get enough Force Gauge to reactivate your Force boost, you get to use it again. And yes, this stacks beautifully with the Gunner Skill Grimoire for Double Action.
Careful usage of Limit Break, Force Reset, and Extend can allow a Fafnir to cheerfully get Accelerate off, hit thrice, then Extend his Force boost for more attacks, before Force Resetting to cancel his transformation and saving his Force Boost gauge. With proper Force management and the (ab)use of Fafnir Grimoires, it is possible, with extremely-minmaxed Limit Break and Force Reset, to get off three consecutive Transforms off a 200% force gauge during a long fight, although in most cases the enemy will be annihilated before you even need to Force Reset even once. Want to take this even further? Your Fafnir can use elemental attacks that will happily set off Element Chaser Landschnekts and Link Order Sovereigns, so Accelerating at the right moment can mean extra Chasing hits from your Landschnekt.
The Fafnir's Force Break, Akashic Nova, scales with the user's experience level and can be made even more powerful by the Compression skill from an Alchemist due to its elemental nature. Want to see you Fafnir happily hit five-digit damage? It is easy.
Resonance qualifies for a slightly different reason. It's a self-charging attack that reaches full power if not used for 3 consecutive turns, and when used at that state it can easily reach quadruple digit damage. What can be done during those other three turns? Using a charge skill just before Resonance hits full power, for instance. And since it's a blade skill that works for katanas and swords, it can be recorded in a Grimoire Stone and given to a Landsknecht, Ronin, or Dark Hunter, so they too can enjoy its incredible damage output in Classic Mode.
Absorb is a skill that allows the Fafnir to cancel any binds and ailments on him, raising his Force gauge in the process. Not only is it a powerful skill for his self-sufficiency, it can be passed by Grimoire to everyone else too, to ensure they can quickly shrug off most debilitating Boss- or FOE- inflicted status attacks.
The War Magus' Ailing Slash. Not only does it deal an obscene amount of damage at high levels, it ignores resistances, so it's a viable skill in nearly every situation.
Their Barrier skill becomes a defensive staple. It functions similarly to Yggdra Vaccinenote 1-turn immunity to ailments and binds, a Purposefully Overpowered King Grimoire skill in The Millennium Girl, only counterbalanced with an activation limit and middling trigger chance at lower levels. But once you push it to max level and support it with max War Lore Mastery, your entire party effectively becomes immune to the first ailments, binds and debuffs for a turn, and its failure rate becomes almost negligible. It is not uncommon to see a single party member constantly throwing up Barrier when they don't need to use any support skills. Even better: if you double up on Barrier with a Grimoire and push it to Level 20, it becomes very reliable with a base 85% success rate, which is easily raised to 100 with a maxed War Lore Mastery.
Crusade. The Troubadour's Force Break multiplies any damage done that turn by 1.5. This wouldn't seem so bad... if the use of other skills from the Troubadour can cause your damage to reach insane levels.
Troubadours in general in this game are pretty overwhelming. The game imposes a much more punishing form of Diminishing Returns for Balance to prevent the player from exploiting buff-stacking for ludicrous amounts of damage. However, it classes the Troubadours' Fantasia skills as an elemental resistance modifier, different from attack or defense buffs. This means they don't get gimped when combined with other buffs, allowing elemental damage to reach new heights. This also compounds with Crusade above, which, due to its status as a Force Break, is also exempt from diminishing returns.
On the topic of Fantasias, the Sovereign's elemental Circles work akin to Fantasias (raising the party's resistance to an element while weakening the enemy's to the same element), do not occupy a buff slot, but only last a turn. In the Japanese version of the game, if multiple party members use it, the effects stack, and this tactic, in addition to the above, is what allows the Fafnir Knight to take down the Bonus Boss in one turn. The stacking does not apply in non-Japanese releases, though.
Venom Curse alongside the food that doubles poison damage dealt. Firstly, the curse is a line spell, which allows it to hit multiple targets. Second, the damage is fairly large at higher levels, while the TP cost is actually fairly low. Third, it's surprisingly extremely accurate without investing any points into Curb Attack Up or Curse masterynote Both of them improve your success rate of making binds and statuses stick due to a lot of enemies - bosses even - being weak to Poison, while their Force Boost (or the Highlander skill, Blood Fortune) is enough to make it work reliably even on things that resist it. The only thing that prevents it from ripping the game in half similar to Revenge in the original is that everything is a Damage Sponge. For perspective, at the regular Level 10 skillcap Venom Curse has about 60 base accuracy, which shoots up to 85 at level 20, with the help of a Level 10 grimoire in Venom Curse. With a Hexer's naturally high Luck and the copious use of Grimoires to push Curse Mastery and Curb Attack Up past level 10, you can easily make Venom Curse (and other status/bind curses) terrifyingly reliable with a base damage of 310 that is doubled by the food buff that increases poison damage to 620, certainly enough to kill or severely weaken enemies in the first 4 stratums easily while taking large chunks out of FOEs and Bosses and enemies that aren't immune from the later stratums.
Grimoire Stones can now be used to boost character skills past the skill cap. It is possible to get a Hexer with Curse Mastery and Curb ATK Up Level 20, allowing them a near 100% chance of landing ailments on anything that isn't immune to them. The aforementioned Ailing Slash? See how much damage it does at Level 20. And that's just scratching the surface of the combos that can arise from the ability to overclock a character's skills.
Rare Grimoires can have powerful secondary passives that contribute to your staying power in battle or make you more effective. Status/Bind Chance Up attributes stack beautifully on Hexers, Survivalists, and Dark Hunters, TP recovery skills add more staying power to your ability to keep spamming attacks, and Elemental Damage Up (Fire/Ice/Volt/Slash/Pierce/Bash) attributes help you minmax your strength to new levels. Even though the bonus is miniscule (6% at best for damage/ailment bonuses) they are additive if combined, resulting in an impressive 36% passive bonus that isn't impeded by diminishing returns for buffs.
In a similar vein to Action Boost from The Millennium Girl, Gunners now have a passive skill, Double Action, which gives the character a chance to use their attacking skills twice in a row. This stacks with the Gunner's own Action Boost (which is now their Force Boost), letting them fire off an attack skill 3 times. But the fun doesn't stop there - Double Action can be passed around through Grimoire Stones, and if it triggers on a skill boosted by a charge skill (which nearly every class learns in one form or another), that second skill also gets that attack boost. Give it to the Fafnir Knight, whose damage output is already ludicrous on his own, and watch him heavily dent bosses with a bit of luck.
Alchemists learn Compression, which temporarily makes their multi-targeting elemental attacks become single-target only in exchange for making them hit harder. Compression works with the Elemental Attack Jars, consumable battle items. Elemental Attack Jars have a specific Forest Cuisine meal from Regina's cafe that increases their damage even more. With Level 20 Compression, a compressed Flame/Frost/Volt Jar (The tier 2 elemental jars that attack all enemies when used) hits harder than any elemental attack in the game (except a compressed Akashic Nova, but then that is a Force Break), even the mighty Flame/Frost/Volt breath Monster skill Grimoires.
Stigmata is a Highlander skill that attempts to bind parts of the user's body before replicating the same binds on an enemy. On a Highlander, it's useless due to their terrible Luck stat. When given to a Hexer via a Grimoire Stone, you can fully bind bosses with ease, especially if this is backed up with the Hexer's Force Boost greatly amplifying their bind/ailment accuracy. If it fails, just try again - Stigmata requires no unbound body parts to execute!
Beyond the Myth
Crossing the Sanzu is essentially a stronger Warrior's Might. It has its drawbacks in that the initiator has to abandon all armour for maximum damage output, the number of chases is capped, and it can chase enemy attacks, but 2400% damage from the physically strongest race with the strongest weapon class is nothing to scoff at. And this is before factoring in effects like the cestus' double damage buff.
The Sovereign Class' skills will add +3 Strength to a character that their Arms skills are used on before subtracting that amount when the skill wears off. However, due to an oversight in coding, this does not apply to stacked casts. If a Sovereign were to cast Fire Arms 10 times on a character, for instance, the game would add +30 to that character's strength before taking away 3. This would cause that character's Strength to be permanently raised by 27. And this can be exploited as much as you want.
Provoke. Enemies will unconditionally go after the Protector when this skill is activated, even if they can't reach said character. This can lead to situations where a frail Runemaster and Hexer are standing between a DOE and the Protector, murdering it, while the monster itself is just standing there and trying to get past the two squishy characters without attacking.
The Protector class itself counts as this, because their defense amplified by certain skills can easily become high enough to effectively nullify most monsters' attacks while taking them all for the team. Theoretically, this would be counterbalanced by their low TP, but for only 3 skill points of investment, they can heal 5 TP with every hit they receive, making even that disadvantage moot.