Mods/Thaumcraft/Taint

Taint is a multilayered affliction, affecting the landscape as Tainted Land, and the player as a Taint status effect. Some tainted areas are created during world generation, either directly or by way of a Tainted ../Node/. However, the player can also create such areas, most likely through careless use of magical implements such as a ../crucible/. Taint can be spawned in creative by spawning a tainted creeper and making it explode. This will spawn taint but it will not spread unless you put down a node in the taint, which will itself become tainted.

Tainted areas tend to spread over time, but slowly. Tainted nodes convert the area around them, but otherwise taint spreads only via fibrous taint, which is blocked by water. However, tainted sheep or creepers can produce fibrous taint (as can pools of flux goo, or, rarely, a Primal Focus). While the taint affects the whole vertical range, it spreads only by fibrous taint, and even in a tainted area, not all blocks may be tainted. A tainted area often extends further underground than the visible corruption on the surface. The spread of taint can be limited with a option in Thaumcraft's config file; if taint spread is disabled, any existing taint will continue to fill in the infected chunks, but will not spread beyond them. Tainted areas can be healed or blocked from spreading, by "pure nodes" (notably those produced by silverleaf trees), or the player's production of ../Ethereal Blossoms/.

A tainted area can be fairly forbidding, starting with the purplish discoloration of land, water, and even sky. Any life that was there before will be infected: Tree trunks will become Crusted Taint (and slump to the ground), while most other plants will become Fibrous Taint. Mobs entering or spawning in the area will be converted to tainted versions or to Thaumic Slimes, and there are several unique monsters found as well, notably the grotesque Taintacle. The player will also be affected -- when passing over tainted areas, they will occasionally suffer a few seconds of the Taint status effect, which may cause damage or other effects.

Taking souvenirs is tricky: Tainted dirt, stone, etc mine as normal materials, and fibrous taint drops nothing. Some of the monsters do drop remains, but getting them home is non-trivial; after 45 seconds in your inventory, they will decay (infecting you with taint for a while). However, tainted relics can be stored in a chest or tossed through a magic hand mirror into storage. They can even be gotten to storage by playing "hot potato" with them, tossing them on the ground and picking them back up every 30 seconds or so. If stored in a donkey or mule's pack, they will not decay or harm the animal, but a tainted biome is not a safe place for such beasts.... Having been collected, taint drops can be distilled for Vitium essentia, which is required to create Ethereal Blooms.

Monsters

 * Tainted mobs -- Most untainted mobs will be "killed" by the taint, but instead of dying, they will be converted either to a twisted version of their former selves, or to a Thaumic Slime. By species:
 * Zombies, skeletons, and slimes are unaffected, though they may get into fights with Taintacles. Endermen will simply teleport away, and will also be unaffected.
 * The usual farm animals (pigs, sheep, cows, and chickens), and also villagers, become tainted versions of their type, which are hostile (and will also attack untainted mobs). Naturally, their new attack inflicts taint on the victim.  Note that tainted sheep can spread taint -- everywhere they stoop to "graze", they will leave tainted soil behind.
 * Creepers will not be attacked by most monsters (Taintacles can set them off), but will eventually be killed by the ground effects, and converted to a tainted form. When these explode, the entire blast radius will be tainted.
 * Other mobs such as horses, wolves, and spiders, have no tainted form, and will become Thaumic Slimes. (Sometimes big ones!)
 * Taintacles: These disturbing creatures grow out of the ground.  While their base is fixed in place, they continually lash out at creatures around them.  They can get in fights with untainted monsters, and also attack each other (which effectively enforces a minimum spacing among them).  They can also attack out-of-reach opponents by spawning several small Taintacles under their feet.
 * Swarm Spawners: These appear as a block of taint interleaved with evil light, but when attacked, they will flash red like a mob, rather than throwing chips like a block.  They produce Taint Swarms, glowing swarms of purple lights which attack passers-by.  Despite the swarm's immaterial appearance, it can be attacked with a weapon in the usual fashion, but the Sword of the Zephyr is particularly effective against them.
 * Thaumic Slimes: Similar to the familiar slimes, but these are more aggressive, faster, and generally larger.  They split when killed like ordinary slimes, but they can also merge with each other.  In older versions, they could grow by absorbing liquid flux, but this has been nerfed as of 4.2.