Paying evil unto evil in tabletop games.
- BattleTech has the Word of Blake, who broke a centuries long Nuclear Weapons Taboo...on civilians. All the other factions in the Inner Sphere proceeded to break the same taboo and nuke them back.
- The ilKhan Bret Andrews of Clan Steel Viper instigated the Wars of Reaving, which pitted the Clans against each other, and killed the Star Adder Khan N'Buta in a fit of rage. This was the last straw for the Clans, and the Star Adder saKhan Banacek killed Bret, and the remaining Clans annihilated the Steel Vipers.
- The In-Universe slogan "Clan Smoke Jaguar Must Die!". The designated 'evil' faction during the Clan Invasion, Clan Smoke Jaguar had subjected the worlds they conquered to harsh repression and crossed a Moral Event Horizon when they used Orbital Bombardment to level a civilian city they had already conquered, a move even the other Clans found repulsive. As a result, the faction was subjected to an outright Annihilation by the Inner Sphere after the Clan Invasion failed, becoming one of the first factions in the game to be outright destroyed to the last and removed from the storyline. Even the other Clans stood by and let the Inner Sphere do it, because of the aforementioned Horizon event.
- A published Call of Cthulhu adventure, Digging Up a Dead God, has the players playing Nazis on an archaeological expedition. Given that it's CoC, and it's almost guaranteed to kill or drive the characters insane by the end, well... Most people would say there's no group more deserving of a horrible ending.
- Dungeons & Dragons has had "Kill Evil and Take Their Stuff" as a motto for decades. And sometimes it's not even that discriminating.
- The Grey Guard prestige class is built entirely around permitting paladins to make exceptions to their code of conduct for the sake of fighting greater evils.
- The Gothic D&D setting Ravenloft encourages DMs to curtail the 'Stab and Loot' mentality, and downplays this trope with the use of Powers Checks (a sort of Karma Meter). It's merely downplayed because said checks are easier to succeed at if you actually paid evil unto evil (Disproportionate Retribution is still a very bad idea). Within the setting, Van Richten, the resident Expert Monster Hunter, strongly advises against indiscriminately slaughtering every creature that opposes them (Lycanthropes could be cured). Ironically, he himself has done this at least once: his origin story includes setting flesh-eating zombies on the tribe of Vistani who kidnapped his son and sold him to a vampire for their own personal profit. (He paid for that one for most the rest of his life, though.)
- The Book of Exalted Deeds, the Good-themed companion to the Book of Vile Darkness, was notorious for this. For example, the Book of Vile Darkness contained several poisons, with notes that using poison is an evil and dishonorable act. The Book of Exalted Deeds then contained several "ravages" - even nastier poisons, some with dramatically horrific effects - and notes that they are fine for Good people to use, because they only work on Evil beings, specifically by turning their own inner evil back on them.
- This is the whole concept of the 5e Paladin's Oath of Vengeance.
- The basic focus of Pathfinder, as with its D&D precursor, is to visit unfortunate ends on evildoers, then abscond with their gold and magic items. However, using spells and actions considered evil on evil targets is still itself considered an evil act, so there's still a line before becoming a villain yourself.
- In Exalted, Green Sun Princes can use this as a loophole to act as something resembling heroes. The terms of their servitude to the Yozis state that they absolutely have to behave in an appropriately evil manner... but the terms say nothing about who they have to target. They can solely target people as bad or worse than they are, and as long as they're sufficiently villainous in dispatching them, it doesn't risk Torment. The net result being that they're no better or worse than any other Exalt, or totally deluded monsters, depending on the campaign.
- Renegade Abyssals also deal in this, since their curse forces them to kill living things, without specifying which ones.
- The HERO System supplement Dark Champions is built around this.
- Hunter: The Vigil has Aegis Kai Doru, a group of hunters who kill magic-users and take their artifacts so that it's easier to kill more magic-users (and sometimes werewolves). The book contains a lengthy section on how to deal with the Karma Meter in light of goals like that.
- Forget about the Greek Indiana Jones. Hunters are the only people who can modify their Moral Code to justify about everything they do, as long as it's in the light of the hunt. The text example has "murdering someone" replaced with "letting a witch/warlock loose". This only makes paying evil unto evil far, far easier for them than other denizens of shadow.
- Elsewhere in the Chronicles of Darkness, the Free Council of Mage: The Awakening have a particular line in this. The Council's Badass Creed has three key principles: "Democracy seeks the truth, hierarchy fosters the Lie"; "Humanity is magical; human works have arcane secrets"; and "Destroy the followers of the Lie" ("The Lie" refers to the barrier between Sleepers and magic). That third one can cause certain issues, however. Because the Council are a radical order with sympathies for mages outside the Pentacle, and they have looser definitions of what behaviour is and is not acceptable in many issues, it's easy to get away with Black Magic within the Council if you only use the darker arts on the Seers of the Throne - whereas Left-Handed Legacies that concentrate on mistreating Sleepers are punished harshly.
- The Left-Handed Path mage book describes the story of the mage Einar, whose entire cabal was wiped out by the Seer Ministry of Geryon. When the other Pentacle mages refused to help Einar get his revenge, he turned to the Abyss and became a Scelestus. Renaming himself Angrboda after the Norse giant who spawned many monsters, he proceeded to summon dozens of Abyssal monstrosities and slowly but surely tore the Ministry apart, pylon by pylon, until he personally cast the Tetrarch down into the Abyss.
- Warhammer 40,000 likes this one, though it must be noted that the setting already runs on Black-and-Gray Morality. The Imperium and Chaos both enjoy sacrificing innocents — the former sacrifice to the Emperor, the latter to the Chaos Gods, to name one example.
- Generally speaking, though, those who run the Imperium want their citizens to die fighting, even if victory on a given field is impossible, so that they can take down as many Renegades, Xenos, or Heretics as they can with their last breaths. Though they do regularly sacrifice hundreds of Pskyers a year to give power to the life-support-reliant Emperor, many of them would've threatened humanity had they been allowed to live as they have no control over their powers (those who have control are sanctioned instead) and said sacrifice is necessary to keep faster than light travel available without which the Imperium would collapse into a second Age of Strife from which it originally arose and lead to extinction at best and Chaos taking over at worst.
- The Forces of Chaos, on the other hand, sacrifice innocents in order to grant the favor of the Dark Gods so they can go on world-molesting crusades, or in particularly evil moments, for fun. However, some Chaos Space Marine players use this to make their army out to be less evil, since the Emperor himself did some pretty nasty things while establishing the Imperium, and that the society itself is very oppressive. From that perspective, the Imperium has to go for the better of mankind. It should be noted that a good chunk of more recent heretics are because of the extreme oppression the Imperium (or rather the planetary authority which answers to the Imperium) shows and slowly becomes the monsters that the Imperium believes justifies its atrocities.
- This perspective spawned the RPG spinoff Black Crusade.
- The Horus Heresy, as the titular novels show, can really be seen as the Traitor Legions doing this to the Emperor for all the crap he did unto them first. Notable examples include snatching Angron away from a Last Stand and leaving the closest thing he had to a family to die (whilst having ample options for saving them all), demolishing a major city just to emphasize his demand that Lorgar Stop Worshipping Me, and refusing to listen to Magnus's warnings about the building Civil War and siccing Leman Russ and his followers onto Magnus's world.
- The Primarch of the Night Lords, Konrad Curze, lived and breathed this trope. His homeworld was a nightmarish city planet where violence and anarchy reigned. How did he bring law and order to the planet? Simple! By becoming an ultra-grimdark version of Batman and The Punisher and brutally murdering every other evil scumbag until the sewers were jammed with their body parts. He was still considered an improvement over his predecessors. After the death of Curze (at the hands of an Imperial Assassin who he let kill him to prove his point about the necessity of this trope) following his joining the traitors in the Horus Heresy and that of his First Captain Jago Sevatarion (who at least somewhat believed in Curze's warped sense of justice), the rest of the Legion abandoned even lip service to justice and became torture and terror addicted maniacs in short order.
- Warhammer Fantasy: Solkan the Avenger, god of vengeance and the sun, directs his followers to use any means, no matter how harsh and brutal, to punish and oppose the minions of Chaos.
- Planescape: One of Sigil's factions (gangs united by a common philosophy) are the Mercykillers (nickname: "The Red Death"), militants who believe The Multiverse is inherently flawed with sin and that perfection can only be obtained by purifying your sins through just punishment. As their name implies, they do not believe in the concept of 'mercy' and any evil is to be punished, violently. They run Sigil's prison system and deal with executions. Crossing them is generally considered a poor idea.
- The spin-off game Planescape: Torment features Vhailor, a member of the Mercykillers considered fanatical even by his faction's standards. His belief in Justice (capital letter included) is so strong it's allowed him to postpone his own death because there are still lawbreakers to punish.
- Zigzagged in Deadlands, in that, whilst some "Gray Hats" are so dark it's outright stated that it's a matter of when, not if, they will become villains themselves, the game still lets some surprisingly dark characters play the good guys.
- Throughout all three lines, there's the Harrowed; a Revenant Zombie with a demonic Enemy Within who can never be removed because it's the source of the Harrowed's undeath, meaning every time they go to sleep, they may end up unable to stop themselves from committing murder and mayhem.
- In the classic game, there's the Huckster, a wizard who literally makes a Deal with the Devil every single time he casts a spell.
- The classic game also rules for a magic using priest who derives his powers from either Aztec Blood Magic or Anahuac (a syncretic mixture of Aztec faith and Catholicism).
- Then there's the Rogue Whatley, who practices Blood Magic.
- The playable vampire is one of those "damnation is inescapable" Gray Hats mentioned above.
- Another comes from Hell on Earth, where the Anti-Templar draws upon the powers of the Reckoners. Ironically, many people consider the Anti-Templars better people than the Templars they oppose, even if they do end up corrupted, since the Anti-Templers both believe they are weakening the Reckoners by leeching away their power and only want that power to protect as many people as possible, whilst the Templars are known for being extremely judgmental and self-righteous.
