The Corruption has a 50% chance of generating or being replaced by The Crimson with (generally up to three) random locations.
The Corruption is recognizable by its background with violet mountains, dead trees, purple grass and darker lighting than other biomes, and is the only biome in which one can find Chasms, Ebonstone, Shadow Orbs and Vile Mushrooms and music change.
Initially, the Corruption can spread to regular grass from corrupted grass so long as the blocks are adjacent. Corrupted grass will also occasionally produce thorns that deal 10 damage and grow indefinitely so long as they are within four blocks of another block.
The monsters found in this biome at any time of day are relatively strong, and are thus a good reason to avoid the Corruption at the beginning of the game.
Monsters found in The Corruption:
- Eater of Souls
- Little Eater (Replaced by different sizes and stats of the Eater of Souls in 1.2)
- Big Eater (Replaced by different sizes and stats of the Eater of Souls in 1.2)
- Corrupt Goldfish
- Corrupt Bunny
- Eater of Worlds (Boss Monster)
- Corrupter (Hard Mode)
- World Feeder (Hard Mode)
- Slimer (Hard Mode)
- Corrupt Slime (Hard Mode)
Hard Mode Changes
After the Wall of Flesh is defeated in a World, the Corruption begins to spread at twice the normal speed, gains the ability to spread over sand and stone as well as turning mud into Dirt Blocks with corrupted grass, and it becomes able to spread across gaps of "incorruptible" material up to two blocks long. Finally, all monsters slain in the Underground Corruption will have a chance of dropping a Soul of Night.
The best and cheapest way is simply by digging a horizontal hole, 6 blocks wide, 3 blocks deep and filling it with any non-biome affectable blocks that cannot be bypassed/corrupted (or hallowed). Examples of blocks: Dungeon Bricks, ores, bricks, clay, ash, silt or blocks that are acquired through crafting(most of them). This method works on ALL biomes and only takes 18 blocks per hole. The Corruption and Hallow cannot spread through clay, bricks, silt, or ash so you can use those materials to your advantage like making a barrier around your base. Sunflowers will also stop The Corruption from spreading pre-Hard Mode.
Another way is to cure the Corruption before defeating the Wall of Flesh, eliminating the preventatives needed to protect your base. However this is a rather hard alternative as, although it has the best results, it is time- and money-wasting, for little or no profit. Also, as the Hardmode spawns more Corruption when you break the Demon Altars, the original biome is not as worth clearing.
Another method is to spread the Hallow on the both sides of your house, as neither the Corruption nor the Hallow can spread across the other. However, hallowed monsters will still spawn which can be an annoyance.
A quick (depends on size) but expensive way to clear the Corruption is by simply blowing it up (with any kind of block destroying Explosives). However, this is very expensive (unless the player has access to a Bomb Statue) and will leave a very big hole, therefore not recommended.
Another (potentially expensive) way to clear the Corruption is to use the Clentaminator to convert corrupted blocks to normal dirt and stone or Hallowed dirt and stone. The Clentaminator uses various colored solutions as ammo, all of which need to be purchased and cannot be crafted. Clentaminate everything, since biomes do spread. Preserving some of the biome is a good idea since sometimes you WILL need that biome (for a boss battle, a Vile Mushroom farm, etc).
However, if the player has a jungle biome blocking the corruption from their home, the corruption will not spread on mud.Therefore, he/she is safe from corruption problems until hardmode, in which the player will have to switch to non-biome affectable defenses.
An artificial Corruption can be created by planting Corrupt Seeds in dirt, and/or by adding around 250 blocks of Ebonstone. This will spawn all monsters from the Corruption, and can be used as a place to summon the Eater of Worlds. Placing any Artificial Corruption close to your home is dangerous as Devourers will spawn and attack you.
Plants/Monsters that Spread Corruption
- Ebonstone (any number of blocks)
- Ebonsand (any number of blocks)
- Corruptor (no longer true after 1.2)
- The player can remove corrupt areas by using Purification Powder or turn them into Hallowed areas with Holy Water.
- The Clentaminator can be used (with purchased solutions) to change blocks into the normal pure forest, the Hallow, the Crimson, or the Corruption.
- If the Dryad is in the world, talking to her and clicking Status will result in her telling what percentage of the world is Corrupt and Hallowed.
- If the thorns touch non-corrupt dirt or trees, they will become corrupt, and further spread The Corruption.
- The Corruption or Artificial Corruption must be used as the place to fight the Eater of Worlds.
- Where The Corruption meets another biome its possible for monsters from both biomes to spawn.
- The Corruption at night is quite dark, therefore remember to bring some form of light.
- The Corruption cannot spread to snow blocks; therefore the Corruption cannot spread through Snow Biomes.
- The Hallow is thought to be the opposite of The Corruption. And equally/more annoying.
- Wood is a cheap but effective material for containing the Corruption or the Hallow.
- The Corruption contains lots of deep holes and falling into one is often fatal due to fall damage. Placing blocks or platforms over the open holes is a good idea to prevent this.
In version 126.96.36.199:
- The spread of the Corruption (plus the Crimson and the Hallow) is slowed after Plantera is defeated in Hard Mode.
In version 1.2, several things changed:
- Corruptor's vile spit no longer spreads corruption
- The Corruption can sometimes be replaced by The Crimson on world creation. It's unknown whether the rules for the spread of the Crimson are the same as the rules for the spread of the Corruption.
- The Corruption can spread to the Snow Biome by changing Ice Blocks to Purple Ice Blocks.
- The Clentaminator was added. It allows you to spread the purity (Normal 'Forest' biome), the corruption, The Hallow, and The Crimson.