Scratch Damage

All successful attacks must inflict some measure of damage, no matter how minor.

You've gotten the Infinity Plus One Sword (or plus more, even), the spikiest, glowiest armor and trinkets in the game, and your Made of Iron stats make you an almost Implacable Man under most circumstances...

...But the snail that randomly appears outside your hometown still does a measly ONE point of damage! In fact, this is the same amount it did when you first started out, and no amount of Level Grinding will ever change that.

For some reason (probably due to the original Dungeons and Dragons), many games absolutely refuse to let a player be utterly invincible and will let even the weakest enemies do token damage long after pure stat calculations should have zeroed it out.

In some games, weak enemies will only manage to inflict damage by landing the occasional Critical Hit. But unless there are other game mechanics at work, like self-inflicted damage caused by a distracting or disruptive attack, they shouldn't be able to hurt you at all with their furry paws while you're wearing your Flaming Armor of Awesomeness, Critical Hit or not.

Fortunately for you, many RPG systems apply Scratch Damage both ways: Your Squishy Wizard's fragile fisticuffs may not be a useful weapon, but even they can be counted on to deliver the token 1 point damage per hit (that is, when they hit), making him Not Completely Worthless even when he's been Silenced or drained of his MP. Likewise, Scratch Damage can sometimes be used to probe for elemental weaknesses: If that magic fireball can inflict at least 1 point of damage, you know that you can Kill It With Fire and don't have to risk casting a Level 100 Holy Hellfire only to discover the enemy is impervious (or worse) to its effect.

But this is by no means universal, and other RPG systems will happily reduce your attacks to zero points or "no effect" if your attack power is too low or the opponent's defense too high.

Occasionally, rare and elusive monsters may be designed entirely around the concept of Scratch Damage, with their total HP measuring in the single digits and even the Party Tank's massive hits are reduced to the token 1 point damage. Expect these foes to be the only times where Scratch Damage is a practical means of attack; other opponents simply have too much HP for the token 1 point to matter.

Scratch Damage is also common in Fighting Games, where a player's Special Attacks commonly inflict a small amount of damage even when blocked, and are referred to as Chipping Damage. It is legitimately possible to KO one's opponent in this manner, but is considered poor sportsmanship (some Street Fighter games would in fact label the victory as "cheesy", with a piece of cheese for the victory icon).

Guaranteed to drive a Munchkin all the way up the wall (and probably through the ceiling due to his optimized Strength...) and is also the bane of those attempting a No Damage Run, especially when coupled with Random Encounters.

If someone dies from this, it's a Death of a Thousand Cuts or Cherry Tapping.

Tabletop RPG

 * D&D contains the Ur-example of this trope, kittycat vs. commoner. Because all attacks must do 1 HP of damage minimum (and damage reduction, which can reduce damage taken to 0, only exists as a higher-level ability). Thus, if an ordinary man and an ordinary cat get in a fight, the cat is very likely to win due to higher agility. And indeed, a gang of five cats is a pretty tough challenge for a low level four-member adventuring party.
 * Pathfinder (aka D&D 3.75) changes this. Minimum damage before DR is 1 point non-lethal damage. Because of low strength, house cats are now incapable of killing commoners in combat. The best they can achieve is knocking the commoner unconscious.
 * Exalted has ping damage, which is the minimum damage you can do (assuming you've hit the target at all, that is.)
 * On the other hand, a heavy suit of artifact armour gives you Hardness, which incoming damage has to beat to have a chance of hurting you at all. Although you will still take ping damage from anything that beats it.

Video Games

 * Thrown rocks in Sly Cooper.
 * In addition to normal blocking, many fighting games provided a "powerblock" feature: If the player defended against their opponent's attack with exact timing (generally right before or upon impact), they would receive zero damage from it, even if it was a Special Attack (which would normally inflict scratch damage). Street Fighter III had this in the form of parrying, and Garou: Mark of the Wolves had it in the form of Just Defend.
 * In the third Star Ocean game, it's possible to get defense stats high enough for attacks to cause zero damage. Getting hit with such a weak attack doesn't even stun you or interrupt your attacks.
 * The Paper Mario titles calculate damage simply as "Attack minus Defense", for both Mario and all opponents, making Spam Attacks (such as Bow's Slap) rarely useful against opponents with even 1 point defense. On the other hand, certain techniques such as Mario's Power Bounce can hit an arbitrary number of times (by Action Commands) but with reduced damage after each successive hit -- if the initial hit inflicted any damage, all subsequent hits are guaranteed to inflict a minimum 1 point per hit.
 * Super Mario RPG generally permitted Scratch Damage both ways, but precise timing on the game's Action Commands made it possible to completely block enemy physical attacks with 0 points damage.
 * The Mario & Luigi series has any enemies always do at least one damage. Also, Mario and Luigi always do at least one damage to enemies. This does mean, however, that the first few hits of multi-hit moves can do 0 damage, but the last one will always do 1. Mario & Luigi: Superstar Saga has an example of this, but it's deliberate. There is an optional boss called Jojora near the end of the game. You have to defeat her friend (a giant snow-doll creature), but it it not necessary to beat Jojora. Many players believe it is actually impossible to kill her; she has the highest defense in the game and every attack only does 1 damage. However, the designers actually intended vigilant players to be able to beat her - she only has 50 HP. A multi-hitting attack will wear her HP down in no time, and she drops a rare item and gives decent experience for your trouble.
 * Other examples of enemies that only take scratch damage from attacks include the tree thing on Trunkle's head (killing it is actually the quickest way to defeat said boss, presuming you use attacks that hit multiple times) and Boos (which have something like a thousand for their defense stats and can only be fought 'normally' at really high levels).
 * Mario & Luigi: Partners in Time has the Gold Koopeleons, which also have the highest defense in the game. They only have 10 HP, and every attack, again, only does 1 damage, with the exception of counters and First Strikes, which can do considerably more, for some reason (even killing them instantly at high enough levels). These enemies have a high speed rating, so they usually move first at normal levels when you first reach them, and they have a high chance of running from battle. However, they drop the most coins of any enemy in the game (80 in the European version and 100 in the US version), which can be doubled, or even TRIPLED with a certain badge. They usually appear in groups of two or three, and if only two appear it is possible to run from the battle and re-engage them, and three might be present! A multi-hitting Bros. Item such as a Red Shell can defeat all three of them in one turn (in the hands of a skilled player); hence it is highly recommended to come back and defeat these creatures once the player's speed rating is high enough to always move first--the rewards are very worthwhile. Using the aforementioned coin-tripling badge, this is easily the fastest way of earning money in the game.
 * Earthbound gets around this by skipping battles against enemies that are far enough below you. You still earn experience and items.
 * In MOTHER 3, they replaced the battle skipping with the dash attack: if you dash into an enemy far enough below you, they disappear. You don't gain any experience or money, probably to give people an incentive to fight higher level monsters as opposed to grinding on low risk enemies.
 * In the NES game Crystalis: if you have strong enough armor and/or a high enough character level, the game's weaker enemies will simply bounce right off you without damage.
 * Of course, the inverse of this is that if you haven't reached an entirely arbitrary level, you will be completely unable to hurt bosses, and unable to run away from the battle, making most of the game a Guide Dang It.
 * Or an exercise in continuous Level Grinding, which was somewhat necessary ANYWAY to get the higher-level armors. The Guide Dang It only comes in the endgame, where you MUST have hit the level cap (and/or found the Power Ring) in order to do any damage to the last several bosses. And then there's enemies that won't take damage at all unless you have the right elemental sword equipped.
 * Fire Emblem averts it -- indeed, even in the course of normal leveling on easy mode your tanks will find a lot of enemies capable of doing a whopping 0 damage, or who have 0% (or 3%, or something similarly pathetic) to hit. Especially on easy mode, or with a Crutch Character at the start of the game.
 * Fire Emblem 4: Seisen no Keifu plays it straight though, no matter how much defense or how weak a character is, they will do at least 1 damage with every successful hit.
 * In Super Robot Wars, certain abilities can reduce damage all the way to zero, although pure defense can't reduce damage below 10 (out of HP totals in the thousands or tens of thousands, mind).
 * In fact, even the seishin spell Fukutsu/Invincible allows a single attack that connects with the unit to deal the minimum of 10 damage. That is, however, subject to cancellation by barriers and shields.
 * In Final Fantasy XI a single digit level monster can still do a critical hit for 1 damage against literally anybody that doesn't use Phalanx. Speaking of which, Phalanx works as a (relatively minor) flat damage reduction, making it pretty easy to set yourself up to take literally no damage at all from anything below level 55 or so. Basically, after the game calculates normal damage, Phalanx can remove a flat number from it based on various stats when it's cast (i.e. 15 damage off the top). So if something did 100 damage to you and you have Phalanx up, it would do 85 damage. This can be used to reduce the damage to 0.
 * FFVII's Debug Room contained test armor which boosted your defense to 255. The damage formula in the game works out such that most enemies in Midgar and the surrounding fields actually heal you slightly when they attack. Enough Morph grinding could net you enough stat boosters to accomplish this effect without the Debug Room.
 * World of Warcraft nearly avoids this in a unique way. Long before the damage would be zeroed out, the level gap will cause almost all attacks to miss.
 * Of course, this also works the other way, and just to make sure people don't get funny ideas, monsters four levels higher than the player will regularly hit low level characters with "crushing" blows that do 150% damage (in addition to an increased critical hit chance), while hits on them will often "glance", dealing half damage. They also pretty much instantly recover their health and mana once they are done smashing you into the ground.
 * The Lord of the Rings Online technically falls victim to this, however the result does not. As players gear up and increase their stats, their in-combat health regeneration will generally negate most damage from weaker enemies, allowing the player to just stand there. In addition, enemies 9 levels or more below the player will normally not aggro. Exceptions are some instances, and the occasional quirk.
 * City of Heroes decreases accuracy and damage per level of difference between player and critter: while there's always a 5% chance for a given attack to hit (or miss, on the other end), the damage they do decreases so much there's often no chance for it to register before the player's health regenerates. Aside from that, the game deals with the issue by having the critters ignore the player if the difference in levels passes a certain threshold. They'll only attack (ineffectively) if they or a member of their spawn take damage from the player or a teammate first. At a great enough difference, they'll all run and not even try to attack back. It, also, of course, works the other way - and much higher-level critters generally will be more aggressive toward player characters (based on distance to first aggro) than even-level critters.
 * Champions Online applies this rule. Especially in the case of the defensive ability of invulnerability, which directly subtracts a flat value from all incoming damage, even enemies tens of levels below you will still be able to hit you for one damage.
 * Damage calculation in the Wild Arms series is done by subtraction, so the little 0 pops up when the player's defense is that high. Can also go the other way with monsters covered in strong armor.
 * All the RPG Castlevania games have a minimum damage of 1 regardless of the attack and defense values involved, unless you use an item that has the absorb or nullify properties for the attack's element. Monsters aren't immune either, and a determined player can eventually kill any enemy with a series of 1-damage attacks.
 * The extreme examples of these being Aria/Dawn of Sorrow's iron golems, who always take only 1 damage from attacks, and Dawn of Sorrow's Dead Crusader soul, which reduces damage by a flat number, making you invincible to weaker enemies. Their attacks still connect, but it does 0 damage and you don't flinch. Comically, the hit effects still occur, which means Soma will still bleed like a stuck pig when hit by an attack that does no damage.
 * Chrono Cross lets you hear the odd strike sound when a weak enemy hits your Rainbow Armoured characters for that wonderful 0 damage. It still counts as a hit for disrupting your attacks and so on, but no damage is inflicted.
 * Fallout 2 featured the famed "You are critically hit for 0 damage and die from the pain." - instant death is also an effect that can occur by critical.
 * Fallout 3 had scratch damage outright due to the removal of armor classes and going to a system where armor simply mitigated damage by a percentage. This was not one of the more popular aspects of the game to say the least. Armor classes returned in Fallout New Vegas, but scratch damage still applies: weapons are guaranteed to do at least 20% damage through armor, which will always means you're going to take at least a point or two of damage from weapons. Given enough BBs and repair kits, you can kill a Brotherhood Paladin with a BB gun.
 * A prime example of why Fighting Games had chipping damage was Iceman in Marvel vs. Capcom 2. He took no chipping damage from 99% of the moves in the game, making him rather popular with Turtlers. It did have one weakness, howerver: War Machine's missiles chipped the hell out of him, making him an ideal choice for those wishing to break the ice.
 * In the three Touhou fighting games, neither player can be killed due to chipping damage. However, because blocking attacks continually drain the defender's Spirit, a player who can capitalize on chain attacks and Guard Break attacks can win anyway.
 * Avoided in popular text-based MMORPG Gem Stone IV, which based damage on a set of calculations that it actually showed you in game: The attacker's strength minus the target's defense, plus a weapon-versus-armor modifier, plus a random d100 dice roll. If the final number is over 100, then a strike is landed - if the number is only around 100-110, it will be a weak hit, while if it approaches 200 you might be removing some important body parts. If the roll ends up under 100, even at 99, then the strike misses completely: for example, if the target's defense is too high for the attacker, and/or their armor is strong against the attacker's weapon. Yes, oddly enough, very strong armor simply causes the attacker to miss entirely.
 * Nowadays times are different, but back in the day it was pretty standard RPG terminology that the word "miss" meant either a literal miss or a hit that did no damage. A bit odd, but that's just the way it was.
 * Chrono Trigger's New Game Plus mode largely averts this - many of the early enemies can do zero damage, and the right combination of armour and equipment can get you about a third of the way through the game without ever losing any HP.
 * Rare Fighting Game (partial) aversions: The Rival Schools, Melty Blood, and Arcana Heart games have chipping damage from special attacks, but chipping can't finish someone off. In the latter, Niptra's "Arcana Force" ability is immunity to chip damage.
 * In the Atelier games, much like Earthbound, if you can get the drop on enemies sufficiently weaker than you, you won't even get into a battle with them (you have a chance to get treasure from them, but not experience).
 * The World Ends With You has your characters completely ignore attacks if they do zero damage.
 * Parasite Eve averts this trope. When Aya's defense reaches its higher levels (at least 200 points or more), most enemies, including bosses, will literally do no damage to you.
 * Jagged Alliance 2 has break lights, when thrown at a character do one point of damage... and cause him (or her) to bleed, requiring basic medical attention to prevent continuing health loss.
 * ...and it's possible to pester NPC's without aggravating them by trying to throw an object (a toolkit, a bottle, a bit of string, or whatever) through them. The thrown object will conk them on the noggin for -1 HP instead. They may eventually even die from bleeding out of their bit-of-string-induced injuries if you stay in that sector long enough.
 * Similarly in Dwarf Fortress's Adventure mode a character with good stats and throwing skill can damage opponents by throwing pretty much anything, including things like berries or clods of dirt.
 * All Nippon Ichi games (the Disgaea series, La Pucelle, Phantom Brave, Makai Kingdom and Soul Nomad and The World Eaters'') avert this trope: With a high enough defence, incoming damage can be reduced to '0'. Piling up the combos can allow otherwise too weak characters to deal damage anyhow, though.
 * There's a certain condition in Ragnarok Online's damage formulas that allows for 0 damage (all attacks that would hit, but deal no damage, will show up as "miss"): Normally, no matter how much DEF or MDEF you have, all attacks will still do a minimum of 1 damage... unless you have special buffs or equipment that reduces damage from a specific source by a percentage (examples: Beret reduces damage of all attacks from Demi Humans by 10%, changing your armor element will alter how much damage each element does to you), which reduces your final damage even further, rounded to the nearest whole number. This is probably due to the same logic that makes all enemies with the Poison armor element take 0 damage from Poison element attacks, because Poison attacks are reduced to 0% effectiveness versus the Poison element on the elemental damage table.
 * Some fighting games (Mortal Kombat, I'm looking at you, although World Heroes 2 Jet did this too) will not only have chip damage from special moves, but will also chip when you block a regular punch.
 * Front Mission wanzers could be chipped to death by much weaker enemies, but later games threw in a skill that would prevent or vastly lower it - damage prevention for attacks below a certain amount, and locking the damage to a lower number for attacks between a certain span.
 * Soul Blazer has a type of armor that will prevent damage from "minor enemies," which comes in handy when you're forced to return to earlier areas of the game to defeat previously unbeatable foes. However, subsequently-obtained armors with higher defense stats will still allow you to be damaged.
 * Xenogears is a prime aversion, since it does allow for 0s, and in this game, leveling up is almost painfully easy, so power gamers see 0s a LOT...
 * On the flip side, scratch damage becomes a valid tactic against certain enemies that are resistant to heavier attacks but have limited HP.
 * Originally avoided in Kingdom of Loathing, but the game was patched with Scratch Damage to circumvent a glitch where hits that connect for 0 damage show "%dmg" for the amount of damage taken. Originally this was a fairly rare sight, since the stat that governs defense is also used for evasion; thus typically a player would become untouchable long before becoming invincible. The bug became much more well known when a skill was introduced that, combined with a shield, let the player use strength for defense instead.
 * Also, any damage of a type an enemy is resistant towards (fire against a hot-aligned creature, a physical attack on a ghost, etc.) is reduced to 1 point per hit.
 * One particular boss takes only scratch damage from any single damage source. In order to beat it, you have to stack up enough different damage sources to deal 350 HP of scratch damage in the 30 rounds given to you before the fight ends in a draw. Fortunately, the boss takes 3 points of scratch damage from elemental attacks it's weak against, and prismatic weapons deal separate scratch damage for every element involved.
 * The Goron Mask in The Legend of Zelda Majoras Mask allows Link to wade though lava unhurt, but he still gets hurt by fire.
 * Zeliard has the player obtain stronger shields later in the game, which will eventually be completely impervious to the game's weakest enemies. An attack from behind will always cause damage though.
 * Shining in The Darkness gives enemies that can't overpower your defense an increased chance to miss and do no damage, but they may still hit for 1 damage every so often. Annoyingly, this does not work in reverse: early on, when your mage is still puny, enemies with sufficient defense will be said to 'shake off the attack' and never take damage.
 * Shining Force Feather sees a lot scratch damage as well: due to the vastly increased HP counts, the ability to grind yourself stupid with little effort and the fact that attacks never miss completely, any enemy is able to consistently hit you for 1-3 damage per turn since everyone has multiple physical attacks per turn. It's ultimately helpful though, since Action Commands allow you to gain some extra Force Points this way, which are used up when doing anything except moving around and using items.
 * In Jade Cocoon, even if you have the greatest defense stat over the enemy's attack stat, you will still take damage. Even though the damage is so tiny you won't see any change in your HP bar, over time it will go down.
 * Also, the game averts this: if you are a high enough Cocoon level, the enemies will be afraid and run away from you before you even encounter. Note that you must be a very high level to get the enemies in the later/end stages to do the same.
 * In Kirby Superstar, both Kirby and his helpers can guard, but depending on the nature of the attack they'll still take some damage or full damage from certain boss moves. A few copy abilities like the parasol gives him an improved guard mode that fully cancels out damage except for the boss moves. In fact, these guards damage enemies on impact, making it possible to beat some bosses purely by Scratch Damage.
 * Starcraft: If a units armor meets or exceeds the attack of whatever hits it, it will take one half point of damage. The game doesn't actually have any kind of half damage mark, so in effect it takes one damage from every other hit. Very few units are heavily armored enough to make this happen. This therefore makes more of an impact on custom games.
 * It IS half a point, actually, as it will sometimes make 0 damage. Basically by all units the damage done alternates between some 80% and 100% percent of possible damage (the more kills the more precise the unit) and "high" damage will correspond to such 1 hit, whereas "low" corresponds to no hit.
 * Even more interested in Warcraft 2: all units with damage low enough to be fully overtaken by some armor (buildings have the best) have a part of damage as "piercing one", which penetrates as if no armor were present. The units with BIG damage don't, so if you tinker armor stats you can achieve that, say, Battleships cannot do even a 1 point damage - but grunts still can do 3-4.
 * Secret of Mana averts this in the form that your characters will simply ninja dodge all weaker enemy attacks. Unfortunately this gets annoying if an enemy can hit fast enough.
 * The Pokémon series's internal damage formula basically boils down to "(attack power / defense power) * (long list of possible modifiers) + 1", thus guaranteeing that all attacks (regardless Status Buffs or Tactical Rock Paper Scissors) will inflict at least 1 point damage. This does not, however, override elemental immunities: Normal attacks still cannot damage Ghosts, and Electric attacks will not damage Ground types.
 * This is used in the "FEAR" (Focus Sash + Endeavor + Quick Attack + Rattata) strategy. Focus Sash will leave you with at least one HP if you were at full health when you took a hit; combine it with Endeavor to make your opponent's HP match your 1 HP. Add in Quick Attack (which strikes first) and the Scratch Damage will finish off the opponent, regardless of how strong they were. Rattata turns the strategy into a catchy name.
 * This is averted in the Pokémon Mystery Dungeon spinoffs, which uses a different damage algorithm; most of the time, enemies weaker than you will do no damage or miss with their regular attack, and even using moves does extremely low damage if they connect at all.
 * In zOMG!, the weakest enemies can still hit a player at the level cap for minimal damage (though the player's innate dodge stat will make half of such attacks miss anyway). Similarly, a low-level player in a high-level area can still hit enemies for 1 point of damage. It is possible to zero out damage, but this is a chance-based property of certain buffs and is not limited to weak attacks.
 * Darth Vader or Yoda blocking with their lightsabers in Soul Calibur IV can still take the damage everyone else does while blocking. It's anyone's guess why they get hurt when some guy punches them in the lightsaber.
 * Final Fantasy XIII has no defense stat (unless you are a sentinel or wearing special armor, at which point you take damage based on a percentage), so creatures that were doing 30 damage to you at the start of the game will still do 30 damage even with your levels maxed.
 * Final Fantasy II (at least the remake version) averts this. If you buy all the best armor before the first dungeon, some enemy attacks will hit some characters for 0 damage, even without level grinding.
 * Final Fantasy V In certain jobs and at high enough levels, enemies just won't deal damage to you. This also means that you cannot do damage to certain monsters, as well (Like Omega, when you first meet him.)
 * Fully justified in Crush Crumble and Chomp; since you're a giant rampaging monster, everyone else is inevitably weaker than you... but those scratches add up.
 * There's a battle in the Game Boy version of Prisoner of Azkaban where Harry, Hermione, and Buckbeak are up against a werewolf-shaped Lupin, and all of your spells will only inflict 1 damage. Buckbeak will inflict more, and if you've stocked up on Chocolate Frog cards you can do about ten damage per round on Harry's turn, but when Hermione comes up to hit, you're in trouble. You pretty much just have to use her to cast her defensive special ability and then spam attack Lupin with Flipendo Uno, which doesn't cost any magic points to cast and still does one damage. Same with Harry if you run out of Chocolate Frog cards to fuel his special attacks.
 * Resonance of Fate has this, any bullet will do at least 1 point of damage even to a heavily armored bodypart. On the other hand, the mechanic literally called Scratch Damage in the game has nothing to do with this trope.
 * Some games, like the Dragon Quest series, handle scratch damage a little differently. If the final damage would normally be 0 or less, the attack has a chance (usually around 50%) of either doing 1 damage or nothing at all. Incidentally, this the only reason the Metal Slime works in those games, since it has maxed out defenses, but very low HP. If every attack did 0 damage, it would be impossible to kill. If every attack did a minimum of 1 damage, it would be too easy to kill.
 * Averted in Just Cause 2. Some things just can't be hurt by handguns and require heavier firepower to destroy.
 * In Civilization V, all units have ten hit points. A stronger unit will do more damage and take less. A much stronger unit can attack a weaker unit in melee combat and possibly not take damage, but ranged attacks always do at least one hit point of damage. A futuristic Giant Death Robot can be taken down by ten ancient-era archer units (or five units with the logistics promotion, which lets them attack twice in one turn). Even four non-promoted archer units could do it in 4 turns with causalities.
 * Averted in Dark Cloud. When Toan's defense becomes high enough, enemies from the first dungeon will do 0 damage to him. Guaranteed if you use a stamina drink.
 * In Prototype, the police, who have a weak little pistol that you can't even obtain due to its uselessness, will always cause at least a bit of damage to a fully-armored Alex. Averted with Alex's powers: punching a tank, even with your superhuman strength, is quite pointless. Only certain powers or combat moves can damage armor. The same goes for hunters, who are immune to bullets and Alex's baseline strength.
 * Prototype 2 will avert this, however. James Heller can become completely bulletproof.
 * Averted in Final Fantasy Tactics Advance and A2: the most basic part of the damage formula is adding Attack/Magick to an ability's attack power (which for a basic attack is 0) then subtracting half of the target's Defense/Magick Defense. It's possible for an attack to do no damage even without Elemental Rock Paper Scissors in account, though that requires a defensive stat at least twice as high as the enemy's attack.

Literature

 * In Conor Kostick's "Epic", the heroes manage to defeat in the world's MMORPG by Zerg-Rushing it.