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 corrupted 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, a corrupted Jungle is merely turned into a corrupted Forest, and is only evidenced by a large quantity of water and mud blocks.

While in Pre-Hardmode, the only biome capable of spreading corruption is corrupted surface Forest with its corrupted 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 enemies like the Eater of Souls and Devourers exist in the biome, presenting dangerous and potentially deadly situations for newer players. The Eater of Worlds can only be summoned in the corruption. The Corruption contains deep chasms, which if not pursued carefully, can result in death from fall damage. Shadow Orbs exist in underground portions of the corruption, mostly at or near the bottom of chasms, in which case you will have to mine to them. Destroying your 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, so it is advised that you gear up before doing so.

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

The Crimson presents more of a red, gory theme, which differs it from its counterpart, the corruption. 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. Like the corruption, the crimson contains red grass, trees and stone. In the crimson, the stone is called crimstone, and can only be mined with a Nightmare Pickaxe/Deathbringer Pickaxe or better. Like the corruption, the crimson contains deep chasms, which can also result in death if not pursued carefully. Instead of shadow orbs, the crimson contains Crimson Hearts. Destroying your first crimson heart will give you the Undertaker and some musket balls, which, like shadow orbs, will instantly 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

Both the Corruption and Crimson will spread throughout a world in pre-Hardmode, and more aggressively in Hardmode:

• Corrupt grass and Crimson grass will spread similarly to normal grass, converting adjacent Dirt tiles with at least one side open to air (only in the Surface Layer).
• Corrupt and Crimson grass can displace normal grass.
• Thorny Bushes can grow in the Corruption and Crimson a distance of 6 tiles in any direction, which can furthermore spread the Corruption and Crimson, even over non-corruptible blocks.
• Non-corruptible blocks (blocks that Corruption and Crimson cannot spread to) include Wood (any sort), Clay, Ash, Silt, Obsidian, Ores, Gems and Bricks.
• Hallowed grass can convert both normal and Crimson grass, and compete with Corrupt grass.

Pre-Hardmode

• Only Corrupt grass and Crimson grass can spread their respective evil biome; Stone ( ), Sand ( ), and Ice ( ) will not convert other blocks and cannot be converted.
• A Sunflower planted on normal grass can halt the spread of both Corruption and Crimson.
• If the player brings Hallowed materials over from a Hardmode world, Hallowed grass (created from Hallowed Seeds or Holy Water) will proceed to spread, converting both normal and Crimson grass, and competing with Corrupt grass. Other Hallowed blocks (Pearlstone, Pearlsand, and Pink Ice) will have no effect.

Hardmode

In Hardmode, the Corruption and Crimson will spread much more aggressively, however defeating Plantera can slow the progression.

• Sunflowers can no longer stop the spread.
• Ebonsand,Crimsand, Ebonstone, Crimstone, Purple Ice and Red Ice will now spread their designated biomes.
• Mud can now be converted to dirt, leaving the jungle vulnerable to the Corruption and Crimson.
• Jungle Thorny Bushes can now be converted to Corruption and Crimson.
• Blocks that are up to three tiles away from an existing Corrupt or Crimson block can be converted (even if incorruptible blocks are in the way).
• Walls can be converted by the Hardmode transition, nearby blocks, or manually by the player, but they do not spread the biomes.

Corrupted and Crimson Deserts

See also: Corrupted Desert, Crimson Desert

A Corrupted Desert.

A Crimson Desert.

In Hardmode, the Corruption and Crimson can spread through the desert, therefore 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 also 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 and crimson can spread out of control, sometimes even taking over an entire world if nothing is done. Therefore, efforts must be made if you don't want your world to be overrun.

In Pre-Hardmode, one can use Purification Powder to remove portions of the corruption/crimson to help slow down the spread. However, it isn't until hardmode that the biomes present much of an issue.

In Hardmode, a good strategy is to dig a 3 tile wide hole around the corruption/crimson, containing it. However, near the surface, Thorny Bushes can spread the corruption up to 6 blocks, so the hole needs to be 6 tiles wide.

However, if you want to make removing the corruption/crimson a feasible task in Hardmode, obtaining the Clentaminator is recommended. Purchasing the Clentaminator requires 2 . It can be purchased from the Steampunker, an NPC who arrives after at least one mechanical boss has been defeated. Purchase green solution from the steampunker, and use the clentaminator to wipe out the corruption/crimson. Note that you should keep small contained pockets of the biome, as the enemies that spawn within the corruption/crimson have unique drops that are required to advance in the game.

Tips

• One way to know if your world has Corruption or Crimson is to ask the Guide. He will tell you to break a Crimson Heart if your 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.
•   In Expert mode, the Vampire Knives are highly useful in virtually all situations. However, the Crimson's boss accessory, the Brain of Confusion, pales heavily in comparison to its' Corrupt counterpart, the Worm Scarf, meaning that the two balance each other out.