A Stock RPG Spell whose damage is proportional to the target's current HP; the most common forms will reduce the opponent's HP by 1/4 (or 1/2) of its current value, weakening the target without killing it.
Like a Fixed Damage Attack, these attacks ignore the game's usual damage calculations altogether, with the only variable being whether or not the attack actually hits the target to begin with.
Naturally, a character at full HP will receive the most raw damage, while characters with low HP will receive hardly any whatsoever. Whether or not this attack is capable of actually landing the killing blow varies by system: The amount of damage inflicted is typically rounded down, so a character reduced to their last Hit Point might receive no damage whatsoever (unless Scratch Damage is required, or if Elemental RockPaperScissors gives it a boost).
Sadly, most Percent Damage Attacks become a Useless Useful Spell in the hands of the player: Despite that enemies have more HP than the heroes (meaning the attack can inflict greater damage), enemies will frequently evade the attack or simply be resistant to them (as a rule), and Bosses have Contractual Boss Immunity against it or have large enough HP pool that any damage the spell does to them usually ends up being capped, meaning they're not any more effective than any other single-hit spell or attack that hits the cap as well.
An occasional variant is calculated using a percentage of the target's maximum HP, rather than their current HP. This is common for percent-based Damage Over Time. Since these types of attacks often kill their targets quickly when left unchecked, some type of Necessary Drawback is implemented to balance it, like a Cap on said attack's maximum damage.
Compare HP to 1, a more extreme attack that removes all but the last Hit Point from its target. If the damage percentage is 100% then you have a One-Hit Kill. Contrast Randomized Damage Attack and Situational Damage Attack.
- The Final Fantasy series has many examples and frequently classifies them as a "gravity" element, featuring versions that remove 25%, 50%, or 75% of the opponent's HP. Some can target multiple foes simultaneously, and are far more likely to succeed when used against your party members than against monsters.
- The Blood Sword of Final Fantasy II drains 1/16th of the target's max HP per hit, making it ridiculously powerful against bosses. Enemies' HP-draining physical attacks in the original Famicom version worked the same way.
- The Demi, Demi2 and Drain spells in Final Fantasy Tactics do 25% (Demi and Drain) or 50% (Demi2) of the target's maximum HP, which is especially significant as the Lucavi boss monsters are fully vulnerable to them, averting Contractual Boss Immunity. In a bit of Artificial Brilliance, said bosses know how dangerous these attacks are, and will treat any units who know those spells as priority targets.
- In Final Fantasy VII, Contractual Boss Immunity is avoided for some flying bosses, who only have a 50% damage reduction from it instead (including one of the two Bonus Bosses). Also, there is at least one enemy that absorbs gravity attacks as HP: Master Tonberry.
- Some monsters in Final Fantasy VII, including a mini-boss, are weak to gravity, which means that a 50% damage attack is effectively a one-hit kill if the monster's HP is less than the 9999 damage cap.
- There is also one Boss in Mook Clothing whose HP total is so high that gravity spells, while still effective, repeatedly hit the damage cap of 9999.
- The Final Boss has an attack with a spectacular animation that takes about two minutes to complete. It seems like an attack that should achieve an easy Total Party Kill, but in fact all it does is take off 15/16 of each of your characters' current HP, so it's actually incapable of killing anyone.
- In Final Fantasy IX and Final Fantasy XII, gravity-based damage is calculated based on an opponent's maximum HP rather than their current HP.
- One of the first battles of Final Fantasy X involves an boss whose only attack is Demi, which is a gravity-based attack that does damage equivalent to a quarter of each character's current HP. Anyone who knows Achilles and the Tortoise knows this boss can't possibly kill you with this attack alone. Lulu (or anyone with the correct items and/or sufficient level grinding) can learn this spell later.
- Several Sinspawn battles (particulary Gui and the power cores) use similar Gravity attacks. The most powerful ones pull out a much deadlier version called Gravija, which cuts HP down to critical level, and then use an area-of-attack elemental spell to finish the job.
- Final Fantasy X-2 has both flavors of percent-based attacks all over the place.
- In Final Fantasy Crystal Chronicles, the "Gravity" spell can be used once per battle against a few bosses to inflict a percentage of damage. It also temporarily immobilizes airborne opponents after damaging them, making them easier to defeat.
- Bravely Default has Bone Crush, which deals damage equal to the difference between the user's maximum and current HP. If the targets are at full or near-full HP, they take Scratch Damage, while if they have half their remaining HP or less, it's a One-Hit Kill. You can get the spell yourself late in the game as Blue Magic (or the equivalent thereof). It also has Dark Breath, Dragon Breath, and Minus Strike, which are somewhere between this and Fixed Damage Attack. Dragon Breath deals damage equal to the user's current HP, while the other two deal damage equal to the difference between the user's maximum and current HP. (Unfortunately for you, those two are also used by bosses....)
- In Persona 4, while most Light element attacks are instant kills, one attack called "God's Judgement" reduces the target's current HP by half. Being part of the Light element, it can still be nullified/reflected by an appropriate Persona.
- Persona 5 has an identical attack, albeit named "Divine Judgement" instead. There also exists Demonic Decree, an identical spell but under the Curse family of attacks. Though these don't work on bosses if you use them, they do work if you can reflect it when a boss uses it on you.
- In Digital Devil Saga, most Hama/Expel spells reduce HP by a percentage with a decent chance of working (both of those depending on the spell), but they will always hit enemies weak to them (Mudo/Death remains a One-Hit Kill).
- The "Super Fang" move in Pokémon reduces the opponent's current HP by half, always doing at least 1 HP of damage. It's most useful when trying to catch a wild Pokémon, allowing the player to inflict Scratch Damage with minimal risk of knocking out the opponent. It is not affected by the game's Elemental RockPaperScissors beyond the fact that "Ghost"-type opponents are immune to its element.
- "Nature's Madness", the signature move of the Tapus, is identical to Super Fang aside from being Fairy-type, a type nothing is immune to. The Tapus also have a signature Z-Move, "Guardian of Alola", which reduces the target's health by 75%.
- The moves "Crush Grip" and "Wring Out" obey the standard damage formula (attack/defense power, Elemental RockPaperScissors, chances of a Critical Hit), but their base attack power is proportional to the opponent's percentage HP. If one strike reduced the opponent's HP by half, the next strike will only hit for half as much.
- Cramorant's "Gulp Missile" deals damage equal to 25% of the opponent's total HP rounded down. Unlike the other Pokémon examples, however, "Gulp Missile" is a passive effect, not an attack, triggered by Cramorant getting hit under certain conditions, and it can have different non-damage effects too, such as the occasional chance of Paralysis if said missile is Pikachu rather than the usual Arrokuda.
- In the Pokémon Mystery Dungeon spin-offs, collateral damage caused by "Selfdestruct" and "Explosion" is always 50% of the teammate's current HP (or if they are Fire-type, 25%).
- World of Mana:
- The Eclipse Dark Tome reduces the target's HP by half in Fire Emblem: Blazing Sword and Fire Emblem: The Sacred Stones.
- In addition to various HP to 1 attacks, Chrono Trigger features several bosses (mainly Dalton and his Golems) who use attacks that drop your health to half of its current state.
- Runescape has enchanted ruby bolts which have a chance to take away 20% of opponent's health from the enemy at the cost of decimating player's health. They're used to take down some of the stronger enemies.
- Golden Sun's summons use the target's max HP to calculate damage, but they also have a fixed base power.
- Inverted in Tales of Maj'Eyal: the Chronomancy spell "Echoes from the Past" deals damage equal to a percentage of the damage the target has already taken rather than how much HP it has left.
- Gnostic abilities in The Logomancer. A 50% one is a reward for completing an early Sidequest, and one inflicting 100% damage can be learned by level up. (Certain enemies also have a variant that inflicts 99% damage.) Interestingly, bosses are not completely immune, just heavily resistant, so they can still be useful against them.
- Continuous Damage in Summoners War: Sky Arena deals exactly 5% of the target's health per turn. Notably, it works on even the bosses, and is the only viable way to kill the Water Guardian.
- Lufia II: Rise of the Sinistrals and Lufia: The Legend Returns have IP attacks that do damage equal to a percentage of the target's current HP. Notably, they always avert Contractual Boss Immunity and are typically necessary for overcoming otherwise Hopeless Boss Fights or Time Limit Bosses.
- The Kingdom Hearts games use the Gravity spells from Final Fantasy as well with their strength being determined by how high Sora's max MP to remove a percentage of remaining HP from bosses, with the added benefit of also flattening enemies and leaving them unable to attack. Although most bosses are immune.
- All Nippon Ichi tactical RPGs (like the Disgaea series) have a poison status effect that each turn inflicts damage based on the target's max HP.
- The Might and Magic series has the "mass distortion" spell that deals a percentage of the target's current health as damage. Usually the damage starts at 25%, and increases based on the casting character's earth magic skill.
- Fell Seal: Arbiter's Mark has several attacks which inflict damage equal to a fraction of the targets current health, like the Knight classs Heavy Hit (1/3) or the Peddler classs Painful Trap (1/2).
- Sir Gareth, a sage-class Knight of the Round Table, in King Arthur: The Role-Playing Wargame has the spell Dragon's Breath. This fantastic attack will halve the hit points of any enemy unit (including any heroes in that stack), making them much easier to defeat. This and other abilities that Sir Gareth has is an indicator of just how powerful a Knight is in the game, as Sir Gareth is gained early - he's only the third recruitable knight amongst many in the game.
- Granblue Fantasy has a few characters and summons (and several raid bosses) with attacks that deal non-elemental damage equal to a percentage of the target's current health. One example is Michael's summon, which at maximum strength shaves off 5% of all enemies' current health (or 999999 if 5% is higher than that).
- In the first Civilization, nukes destroy exactly half of a town's current population, including defending units and one significant structure.
- The Sorceress in Diablo II has the Static Field skill, which does damage equal to 25% of target's current HP including bosses. Resistances and immunities apply. On Nightmare and Hell difficulties, this skill cannot reduce the health of enemies below 33% and 50% respectively. Against other players, it does only 4.375% damage after applying PvP damage reduction.
- The Crushing Blow item modifier provides a chance to reduce the HP of target monster, boss, or hostile player by 1/4, 1/8, and 1/10 respectively with each successful attack. This works with ranged attacks but the effect is halved.
- Worms has the Battle Axe in some games, which halves the victim's current health. This percentage can actually be changed via the power setting in the scheme editor from as low as a quarter to as high as three quarters, making it a decisive weapon in high HP schemes or if that one bugger is hoarding all the health. If you want to get really creative, you could slice your own team's health down with the axe and then follow it up with the Scales of Justice to bring your enemies down as well.
- In DROD RPG: Tendry's Tale, stepping on a hot tile takes 5% of HP; stepping through an Aumtlich beam takes 50%. Optimisation often requires leaving healing potions untaken so your HP is low when you incur the percentage attacks, then taking them afterwards.
- Defense of the Ancients has Huskar's ultimate, named Life Break, which does this to himself as well as his opponent, with the damage he takes being reduced as it's leveled up.
- Necrophos specializes in these kinds of attacks: Heartstopper Aura slowly drains away a small bit of health based on the target's max HP, and Reaper's Scythe deals extra damage based on missing HP, fitting with its status as a Finishing Move.
- This kind of damage, applied to a hero's right clicks, can make them a carry. Lifestealer's Feast lets him rip through opponents with high Str and/or items giving a lot of health, and Viper's Nethertoxin, while increasing at set points, functions as a "damage increases as enemy HP decreases" effect that will quickly bring down anyone under 20% HP, since the damage scales exponentially and the bonus damage from only two attacks at that point deals about the same amount of damage as a standard nuke spell.
- Dungeon Fighter Online: Most endgame bosses, especially those in raids, have attacks that chunk a percentage of the player's maximum health. This is ostensibly to encourage avoiding attacks and to discourage tanking through them with large health pools and/or heals from classes that aren't explicitly a Support Party Member.
- In Heroes of the Storm:
- Many heroes can pick talents that cause their basic attacks to deal extra damage based on the target's maximum health, most commonly being Giant Killer and its variants, which deal anywhere between 1.5% to 3% of the target's Hit Points as damage.
- Kharazim can use one of of his two heroic abilities, Seven-Sided Strike, to deal 7% of the target's Hit Points as damage seven times to enemy heroes in an area. Given that he's primarily a Combat Medic, the ability damages the highest-health target in the Area of Effect each strike, so it's generally going to soften targets up rather than get kills. However, if you can get an enemy isolated, Seven-Sided Strike can kill any hero in the game by itself.
- Malthael is this trope taken to its Logical Extreme. His trait, Reaper's Mark, marks enemy non-structures he damages with basic attacks, causing them to take an additional 2.5% of their max health in damage every second for 4 seconds. And one of his heroic abilities, Last Rites, damages a target based on their missing HP, making it a Finishing Move if the target has less than 33% of their max Hit Points remaining.
- Where Malthael is great at whittling targets down, Tychus is the premier burst tank-buster. His trait, Minigun, can be activated to let him to deal 2.5% of the target's max HP per basic attack for three seconds. He attacks four times per second by default (With a particular quest talent, this is taken up to five times per second), meaning that that is a whopping 10% of the opponent's max health gone per second. He also gets a variant of Giant Killer for one of his level 16 talents (which does stack with Minigun), and the Titan Grenade talent applies this to his Frag Grenade, which makes it inflict 5% of the target's maximum health as extra damage.
- Pretty much a staple of League of Legends in several variations as below. Designed as a major tactical decision for a player, since percent damage works extremely well against characters with lots of HP but few other defenses, but is very ineffective against people with low HP that rely on healing or armor to defend themselves. Certain types of percent damage attacks are more common for certain archetypes:
- Damage set at a percent of target's current HP level, usually used by champions gearing up to kill HP tanks (e.g. Dr. Mundo's cleaver, Liandry's Torment).
- As a percentage of total HP, usually used for offensive spells to discourage buying HP in favour of resistances (With exception to Vayne, whose total HP based damage passive ability deals true damage and cannot be reduced).
- As a percentage of the caster's own HP, often owned by tank characters to encourage buying HP boosts (Sejuani, Shen)
- As a percentage of the target's missing HP and usually called an "execute", used by assassins (e.g. Kha'zix) to finish off foes one-on-one (damage increasing the longer the fight goes on instead of decreasing.)
- There is also percentage healing: Soraka's healing abilities are increased by 1% for every 2% of the resource the target is missing, Zac heals 4% of his maximum health if he collects the blobs shed by casting spells, and Dr. Mundo does both damage and healing by spending 20% of his current health to heal up to 60% of his maximum health.
- Warcraft III: The Death and Decay spell damages for 4% of a unit's total life per second, and lasts for 35 seconds.
- Several spells do percent buffing: The Trueshot Aura increases ranged damage by 10, 20 and 30% (just 10 for the unit version), Roar gives all friendly units a temporary 25% damage increase, and Command Aura gives all units in range a 15% damage increase.
- Played with in Team Fortress 2, where the Spy's Back Stab does damage equal to a certain percentage of the target's health—namely 200% of it. And it has a 100% chance to crit, making the effective damage 600%. For most purposes this makes it indistinguishable from a One-Hit Kill, but in certain conditions (most notably using the Dead Ringer) the target may have enough damage reduction that can survive the hit.
- Several monsters in Puzzle & Dragons have percentage damage active skills, which take a percentage of the current health of all opponents, though these skills will have longer cooldowns at higher potencies. Several dungeon monsters have this among their attack, going as far as 1000%, something that can only be tanked by either a damage nullifying active or stacking damage shield leader and active skills, and there are only a handful that can do that.
- Outpost Defenders has many items that deal a percent of the target's health. Usually, they are more expensive than other items, and they often only deal around 10% damage, making them only good for bosses.
- Enemies in Crash Fever are able to do this, with how large the percentage is and whether it is based on your current or max hp varying from quest to quest. Some of your units can also do these kinds of attacks as well, mostly through skills.
- Command & Conquer: Red Alert: The M.A.D. Tank is the only unit in the game that deals percent-based damage. It hits all enemy and ally vehicles and structures in a wide area around it before self-destructing, dealing around 35% of their max HP in damage. This means that three M.A.D. tanks clumped up together are pretty much guaranteed to kill all vehicles and structures around them if they blow up in quick succession.
- Lobotomy Corporation has pale damage, a Percent Damage Attack Type. 1 point of pale damage means losing 1% of an employee's maximum health; therefore, receiving 100 points of pale damage is invariably fatal. Against an Abnormality, however, it merely deals standard damage, like any other attack type.
- Kingdom Rush Vengeance: Ice dragon Eiskalt has the "Ice Peaks" skill, which summons a wave of icicles that jut out of the ground dealing 30% of an enemy's max HP if they connect. If the player is lucky, the icicles can hit a Giant Mook twice, removing a huge 60% of their max health.
- The word "decimate" originates from a Roman military punishment, wherein soldiers found guilty of cowardice were ordered to draw lots, with one out of every tennote men being executed as a result. The term is rarely used that way any more.
- Awful Hospital: Willis' unique "Drink" ability steals 25% of the target's current Hit Points. As it's his only means of attack, he's a powerhouse against Damage Sponges, but struggles to finish anyone off — a point of Gameplay and Story Segregation.
- The concept of Day-fine, where fines are tied to your personal income. There's no Screw the Rules, I Have Money! here; break the rule, and you will feel the sting, whether rich or poor.