The Corruption

Every world contains either The Corruption or its counterpart The Crimson, generated randomly with a 50% chance each or chosen by the player upon world creation.^[1] The Corruption surface includes purple Corrupt grass, Corrupt Trees, Vile Mushrooms, and purple thorny bushes that damage the player on contact.^[1] Water in The Corruption appears purple, and the biome contains chasms that lead downward in straight lines, some crossing horizontal connectors and ending with a Shadow Orb.^[1] Demon Altars line the chasm passages, and chasms consist of Ebonstone, which can be mined with a Nightmare or Deathbringer Pickaxe or higher, blown up with explosives, or purified to Stone.^[1]

The Corruption spreads by converting adjacent susceptible tiles, spreading slowly in pre-Hardmode and much faster after defeating the Wall of Flesh; defeating Plantera reduces spread speed by 50%.^[1][2] A dark purple wasteland with death and decay motifs, the Corruption is an evil biome that looks like a twisted forest.^[1] A minimum of 300 tiles of Corrupt grass or Corruption blocks are required for an area to qualify as a Corruption biome.^[1] Chasms, Demon Altars, and Shadow Orbs are generated only when the world is created; they do not appear in Corruption zones that result from biome spread.^[1]