Evil Biome

An Evil Biome is a naturally spreading, hazardous biome that has generally negative effects on entities inside or around it. The Corruption or The Crimson will always spawn in a world. A generated world will only contain one of the two biomes, with a 50/50 chance of one of them generating. If a player has entered Hardmode in at least one world, they can choose whether they want Corruption or Crimson to generate in their world. However, they can still leave it up to the 50/50 setting.

This biome is saved as the world's naturally generated Evil Biome, and determines:

• Whether Shadow Orbs or Crimson Hearts are generated
• Whether Demon Altars or Crimson Altars are generated
• Whether a Corruption Chest or Crimson Chest is generated in the Dungeon
• Whether Underground Corruption or Underground Crimson is created when the Wall of Flesh is defeated
• Whether Corruption- or Crimson-related blocks are seeded as Altars are smashed in Hardmode
• Whether some NPCs will sell Corruption- or Crimson-related items during a Blood Moon or Solar Eclipse
•    Which Biome Mimic is spawned when a Key of Night is placed in a chest

These will not be affected by artificial Corruption/Crimson (which can be created from materials brought over from another world).
The type of Biome Key    / Biome Key Mold  dropped by enemies is dependent on the biome the enemy is killed in, regardless of whether it is a "natural" biome or "artificial" biome.

The biome is predominately comprised of chasms made from infected stone (Ebonstone or Crimstone). However, the biome can overlap other biomes, providing corrupted versions of the Forest, Desert, Snow, Jungle or Ocean biomes. This can be evidenced by the presence of purple/red grass and Ebonwood/Shadewood trees, purple/red Cactus and Ebonsand/Crimsand, Purple Ice/Red Ice, or purple/red Palm Trees. Unfortunately, infected Jungle areas turn into corrupted Forest (with the mud converted to dirt). This makes such areas much harder to recover, though the presence of Chlorophyte ore can help.

While in Pre-Hardmode, the only biome capable of spreading the evil biomes is infected surface Forest, via infected grassy blocks (see below for details).

Corruption and Crimson exclusives

Certain items are exclusive to either The Corruption or to The Crimson.

The following items are considered counterparts to each other. It should be noted that counterparts do not share the same stats. This content is transcluded from Corruption and Crimson counterparts.

The Corruption	The Crimson	Source
Musket	The Undertaker	Shadow Orbs / Crimson Hearts
Vilethorn	Crimson Rod
Ball O' Hurt	The Rotted Fork
Band of Starpower	Panic Necklace
Shadow Orb (item)	Crimson Heart (item)
Rotten Chunk	Vertebrae	enemies
Cursed Flame	Ichor
Vile Mushroom	Vicious Mushroom	Corrupt / Crimson grass
Demonite Ore	Crimtane Ore	Eater of Worlds / Brain of Cthulhu, environment, Eye of Cthulhu
Shadow Scale	Tissue Sample	Eater of Worlds / Brain of Cthulhu
Eater of Worlds Mask	Brain of Cthulhu Mask
Eater of Worlds Trophy	Brain of Cthulhu Trophy
Eater's Bone	Bone Rattle
Worm Scarf	Brain of Confusion	Eater of Worlds Treasure Bag / Brain of Cthulhu Treasure Bag
Dart Rifle	Dart Pistol	Corrupt Mimic / Crimson Mimic
Clinger Staff	Life Drain
Putrid Scent	Flesh Knuckles
Chain Guillotines	Fetid Baghnakhs
Worm Hook	Tendon Hook

The Corruption

Chasms of The Corruption

The Corruption presents a purple "corrupted" theme, with purple grass, trees and stone. Thorny Bushes and unique enemies (beginning with Eaters of Souls and Devourers) make the area dangerous and potentially deadly for newer players. The Eater of Worlds can only be summoned in the corruption. The Corruption contains deep vertical chasms (which can easily result in death from fall damage), with cross tunnels well below ground. Shadow Orbs appear deep underground, usually at or near the bottom of chasms. Destroying a world's first shadow orb will always drop a Musket and some Musket Balls, which automatically fulfills the criteria for the Arms Dealer to arrive. Destroying 3 shadow orbs will result in the spawning of the Eater of Worlds.

Corruption Contents

Characters

Pre-Hardmode:

• Eater of Souls
• Devourer
• Eater of Worlds(Boss)

In Hardmode:

• Corruptor
• Corrupt Slime
• Slimer
• World Feeder

From killed Corrupt Slime/Shadow Slime:

• Slimeling(3 spawn at once)

Corrupted Desert:

• Dark Mummy
• Shadow Mummy 

Underground Corruption:

• Cursed Hammer
• Shadow Hammer 
• Clinger
• Corrupt Mimic  

Unique Treasures

From Shadow Orbs:

• Ball O' Hurt
• Band of Starpower
• Musket
• Musket Ball
• Shadow Orb (item)
• Vilethorn

Unique Drops

From Eater of Souls:

• Ancient Shadow armor

From Eater of Souls, Devourer, Corruptor:

• Rotten Chunk

From Devourers:

• Worm Tooth

From Eater of Worlds:

• Shadow Scale
• Eater of Worlds Mask
• Eater of Worlds Trophy
• Eater's Bone

From any enemy in Hardmode:

• Corruption Key(from any enemy, 1/2500 chance)   
• Corruption Key Mold (from any enemy, 1/2500 chance)

Underground Corruption:

• Soul of Night(1/5 chance)

From World Feeders and Clingers (Hardmode):

• Cursed Flame

From Corrupt Slimes and Slimelings (Hardmode):

• Blindfold

From Cursed Hammers:

• Nazar

From Shadow Hammers :

• Cobalt Bar
• Mythril Bar
• Adamantite Bar

From Corruptors (Hardmode):

• Vitamins

From Dark Mummies (Hardmode):

• Blindfold
• Dark Shard
• Megaphone

From Corrupt Mimics  :

• Dart Rifle  
• Worm Hook  
• Chain Guillotines  
• Clinger Staff  
• Putrid Scent  
• Greater Healing Potion
• Greater Mana Potion

From vegetation:

• Vile Mushroom
• Deathweed
• Deathweed Seeds(during Blood Moon)
• Ebonwood(from trees)

From terrain:

• Ebonstone Block
• Ebonsand Block
• Purple Ice Block(Snow biome)

From Fishing:

• Ebonkoi
• Purple Clubberfish
• Toxikarp  
• Corrupt Crate  

For Sale

From Painter:

• Lightless Chasms

The Crimson

Chasms of The Crimson

In contrast to the Corruption, the Crimson presents more of a red, gory theme, with red grass, stone, and foliage. Unique enemies that only appear on a crimson world include Blood Crawlers, Face Monsters and Crimeras. The Brain of Cthulhu, the alternative to the Eater of Worlds, can only be summoned in the crimson. Crimson-infected stone is called crimstone, and like its corruption counterpart, can only be mined with a Nightmare Pickaxe/Deathbringer Pickaxe or better. Like the corruption, the crimson contains deep chasms, but these are differently shaped: A winding tunnel from the surface leads to a large cavern, with secondary tunnels spreading downward from the cavern. While long falls are less of a hazard here, the area is still quite dangerous. Instead of Shadow Orbs, the Crimson contains Crimson Hearts, placed at or beyond the end of the secondary tunnels. Destroying a world's first crimson heart will drop the Undertaker with some musket balls, which, like their Corruption counterparts will fulfill the criteria for the Arms Dealer to arrive. Destroying 3 Crimson Hearts will result in the spawning of the Brain of Cthulhu.

Contents

Characters

Pre-Hardmode:

• Blood Crawler
• Face Monster
• Crimera
• Brain of Cthulhu(boss)

In Hardmode:

• Herpling
• Crimslime
• Blood Jelly
• Blood Feeder

Crimson Desert:

• Dark Mummy

Underground Crimson:

• Crimson Axe
• Ichor Sticker
• Floaty Gross
• Crimson Mimic  

Unique Treasures

From Crimson Hearts:

• The Undertaker
• The Rotted Fork
• Crimson Rod
• Panic Necklace
• Crimson Heart (item)  

Unique Drops

From Blood Crawler, Crimera, Face Monster:

• Vertebrae

From Brain of Cthulhu:

• Tissue Sample
• Bone Rattle  
• Brain of Cthulhu Trophy
• Brain of Cthulhu Mask

From any enemy in Hardmode:

• Crimson Key(from any enemy, 1/2500 chance)   
• Crimson Key Mold (from any enemy, 1/2500 chance)

Underground Crimson:

• Soul of Night(1/5 chance)

From Dark Mummies(Hardmode):

• Blindfold
• Dark Shard
• Megaphone

From Herplings and Crimslimes(Hardmode):

• Meat Grinder

From Crimson Axes:

• Nazar

From Ichor Stickers:

• Ichor

From Floaty Grosses:

• Vertebrae
• Vitamins
• Meat Grinder

From Crimson Mimics  :

• Life Drain  
• Dart Pistol  
• Fetid Baghnakhs  
• Flesh Knuckles  
• Tendon Hook  
• Greater Healing Potion
• Greater Mana Potion

From the terrain:

• Crimstone Block
• Crimsand Block
• Red Ice Block(Snow biome)
• Shadewood
• Vicious Mushroom  

From Fishing:

• Crimson Tigerfish
• Hemopiranha
• Crimson Crate  

From Fishing in Hardmode:

• Bladetongue  

For Sale

From Painter:

• Deadland Comes Alive

Spread

Main article: Biome spread

Both the Corruption and the Crimson will spread themselves, similar to the Hallow. This means that they slowly convert certain susceptible tiles that are in the vicinity of existing Corrupt/Crimson blocks. While their spreading capabilities are very limited during pre-Hardmode, they spread much faster and more aggressively after defeating the Wall of Flesh. Defeating Plantera for the first time reduces the overall spread speed of all three biomes by 1/2 (50%).

Corrupted and Crimson Deserts

Main articles: Corrupted Desert, Crimson Desert

A Corrupted Desert.

A Crimson Desert.

The evil biomes can overlap deserts, and in Hardmode, can spread through them, creating Corrupted and Crimson deserts. In the Corruption, sand is replaced with Ebonsand, and in the Crimson, sand is replaced with Crimsand. Unique enemies not found in the normal Corruption and Crimson can be found in the biome's desert variant.

Purification

See also: Guide:Maintaining world purity

A properly contained Corruption and Hallow, which, while not considered an evil biome, can eventually spread out of control.

In Hardmode, the Corruption or Crimson (like the Hallow) can spread out of control; without player efforts, the evil biome and Hallow with together take over the entire world.

In Pre-Hardmode, players can use Purification Powder to purify small portions of the corruption/crimson, and Sunflowers to block spread of infected grass. However, it is not until Hardmode that the spreading biomes become a major issue.

In Hardmode, a good strategy is to dig 3 tile wide tunnels around the corruption/crimson, containing it. However, near the surface Thorny Bushes can spread the corruption up to 6 blocks, so the tunnels there need to be 6 tiles wide or lined with non-corruptible blocks.

Removing the Corruption or Crimson wholesale, or reversing its spread in Hardmode, effectively requires the Clentaminator. This can be purchased for 2  (one of the most expensive items in the game) from the Steampunker, who arrives after at least one mechanical boss has been defeated. Using the Clentaminator with Green Solution (also purchased from the Steampunker) can purify large sections of the evil biomes. However, most players will want to keep some well-contained pockets of the biome, as the enemies there have unique drops (some of which are required to advance in the game).

The evil biomes are also blocked by the presence of the Hallow, and vice versa; even before obtaining the Clentaminator, seeding the Hallow is an alternate strategy to limit the spread of Corruption or Crimson.

Tips

• One way to know early (before exploring the world) if a world has Corruption or Crimson is to ask the Guide. He will tell the player to break a Crimson Heart if the world has Crimson, or to break a Shadow Orb if the world has Corruption.
•    In 1.3, one-half of the world generation progress bar will be green, and the other half purple or red, depending on if the world is to have Corruption or Crimson. The step in world generation in which the Crimson is created is called "Making the world bloody", and the step in world generation in which the Corruption is created is called "Making the world evil". Also, a tree at the side of the world name in world selection has one green/normal side, the other purple/red (indicating Corruption/Crimson respectively). In Hardmode, part of the tree will be yellow, representing the Hallow.