Corruption is a mechanic in the campaign mode of Total War: Warhammer and it's sequels. Corruption represents the dark influence of certain nefarious races in a province on the campaign map, and is shown on the Province Info panel. Excessive corruption in a province usually benefits the spreading race, while harming other races. The opposite of corruption is being Untainted, which can also be spread.
Corruption physically changes the appearance of the campaign map.
Broadly speaking, factions which do not spread corruption are harmed by corruption effects, taking hits to public order and even attrition damage if total corruption exceeds 50%. However, even a faction with it's own corruption to spread can be harmed by other types of corruption. For instance, Vampire Counts can be harmed by Chaos corruption.
Spreading corruption does not, by itself, affect diplomacy with other factions. However races who spread corruption tend to not get along well with others.
Some army stances can protect that army against corruption and attrition.
Characters belonging to other factions may gain certain traits when spending too much time in corrupted regions.
Untainted is anti-corruption, or the absence of corruption. Factions which do not spread corruption tend to have buildings, commandments and character abilities that reduce corruption/increase untainted.
Untainted was added in Total War: Warhammer II. Prior to this, effects would just say something like "reduction in vampiric/chaos corruption".
- The Empire, Dwarfs, Bretonnia, Greenskins, High Elves, Wood Elves, Tomb Kings and Lizardmen do not spread corruption, instead spreading untainted.
- Skaven spread both Untainted and their own Skaven Corruption (see below).
- Most Dark Elves factions do not spread corruption and instead spread Untainted. The exception is Morathi's Cult of Pleasure who spread Chaos corruption.
- Factions which do not spread corruption are harmed by all types of corruption, and will take attrition damage in provinces with over 50% total corruption.
- Spreading Untainted reduces all kinds of corruption.
- During the Old World and Mortal Empires campaigns, the Chaos Invasion event increases Chaos Corruption across the entire map.
- Provinces with a Chaos Wasteland climate, such as The Chaos Wastes, have naturally high Chaos Corruption.
- Certain character abilities increase Chaos Corruption, as does the mere presence of armies and settlements from the above factions.
- Warriors of Chaos, Norscans and Beastmen all have special options to raze a settlement while erecting a monument of the Chaos Gods. These monuments increase Chaos corruption in nearby provinces.
- Chaos corruption causes the land to turn grey, lava rifts open in the ground, and brief daemonic shadows are seen. In battle maps the sky turns red and begins to rain down ash. The ambient sound becomes darker.
Spending too much time in Chaos-corrupted regions will result in the character trait:
- Insane: Melee Defence -15, Public order -5, Weapon Damage +20
- Vampiric corruption gives the campaign map a blueish-grey tint. Trees begin to die, and ghosts are seen. The ambient sound also changes to include howls and screams.
- Vampiric corruption represents both actual vampires infiltrating other societies, as well as the dark magic and actual darkness covering the land.
- Vampire Counts armies take attrition damage when in provinces with low Vampiric Corruption.
- Certain Vampire Counts buildings spread Vampiric Corruption by burning ghostly green balefires. Additionally, Vampire Counts heroes and armies spread corruption.
Skaven corruption is spread by all Skaven factions.
- Skaven corruption does not cause attrition when it reaches 50%.
- Skaven corruption only subtly affects the appearance of the campaign map, with a few Skaven burrows and chunks of warpstone appearing.
- It is the only type of corruption which has negative effects on the race spreading it: Skaven corruption lowers Public Order for the Skaven. Capped at -5.
- The damage to public order (for self) is capped at -5, allowing it to be controlled with public order buildings rather than untainted on lower difficulties.
- Higher levels of Skaven corruption in a province, allow extra uses of The Menace Below at no food cost (up to a maximum of 6).
- Due to the public order downsides of Skaven corruption, Skaven are encouraged to not compound public order penalties from a lack of food as well. However, it is still possible to colonize at higher tiers if food production is high, and losses can be recouped quickly.
- High corruption generates the negative trait, Skaven Denial, in non-Skaven lords. This trait grants the lord a public order bonus of +1 (local province), and a massive -15 leadership penalty when fighting Skaven (self). This debuff effectively renders any leadership skills taken by the enemy lord useless, unless they total more than +15 or the trait is removed by wasting several turns in an uncorrupted location.
Spending too much time in corrupted regions will result in Skaven skeptic trait: Public order +1, -15 leadership when fighting against Skaven