As soon as you enter Hardmode in Terraria, the world's Corruption, Crimson, and the new Hallow biome all start to expand outwards. Rapidly. If left to their own devices, these biomes will eventually swallow your entire world, destroying your NPC villages and making life generally difficult.

Related: Terraria: Best Placement For All NPCs

Thankfully, there are a variety of different ways you can remove Corruption and Crimson from your Hardmode world. This guide covers everything you can do to prepare for Hardmode's evil biome spreading, and what you can do in the endgame to remove it entirely.

Updated April 9, 2023 by Jacqueline Zalace: Corruption and Crimson in Terraria can be a bit annoying to deal with. Because of this, we've added more information to help you deal with these evil biomes. Additionally, we've added some tips for dealing with the Hallow.

What Are Corruption And Crimson?

Corruption and Crimson are the main evil biomes of your world. Each world will spawn with either a Corruption or Crimson biome, though there are one or two rare seeds that will spawn both. You can choose whether you start with a Corruption or Crimson world before you start generating it.

The biome will determine which bosses you face, like the Brain of Cthulhu for the Crimson and the Eater of Worlds for Corruption. This will also dictate what sort of armor and weapons you can create before you enter into Hardmode.

Overall, these two modes are the same difficulty, so it's up to you which one you want to face in your world.

How The Spread Of Corruption And Crimson Works

Both biomes will slowly spread, even before Hardmode. They convert nearby blocks to the same biome at a very slow rate. in pre-Hardmode, they only spread through grass and bushes. Converted areas will have the same background music, spawn the same enemies, and grow the same plants.

Specific biomes, like the Desert or Snow biome, will have unique versions of the biome when converted into either Corruption or Crimson. For example, the Crimson Desert will spawn enemies like the Blood Mummies on the surface, and Dark Lamias underground. The Snow Biome has no unique enemies, but the Ice will convert to Red Ice.

Every Altar you smash will also increase the speed of Evil biome spreading. Be careful.

Corrupted biomes spread particularly quickly through soft blocks, like snow, and mud. This means that Deserts, Snow Biomes, and the Jungle are very susceptible to the quick spread of the corrupted biomes. As a result, the Jungle biome can very quickly become completely overrun if it is near the evil biome.

Hardmode Spread

Things get more complicated in Hardmode. Not only does the rate of spread increase significantly, but the evil biomes will also spread through stone and vines, which means Corruption or Crimson will spread underground, not just on the surface.

Corruption and Crimson can now spread through sand, mud, grass, stone, and pretty much every default natural block.

The rate of spreading is sped up as soon as you defeat the Wall of Flesh and enter Hardmode. However, this rate is then decreased once you defeat Plantera.

This should stop the biomes from spreading super quickly if you haven't prepared your world. You can rush this boss, if you're capable, and reduce the risk of your world becoming overwhelmed.

What Is The Hallow?

The Hallow is a third, spreading biome that will only be present once you make it to Hardmode. After defeating the Wall of Flesh, a portion of your world's evil biome will become Hallow.

Like Crimson and Corruption, Hallow will spread. Overall, it will spread with similar mechanics. Although the biome is 'cute' in appearance, the mobs are still dangerous. Interestingly, the two evil biomes cannot spread through the Hallow, and vice versa. If these biomes ever meet, the spread will stop.

Unlike Crimson and Corruption, Hallow cannot spread through mud blocks or the Glowing Mushroom Biome.

Digging Holes To Stop Biome Spread In Pre-Hardmode

This method is very time-consuming but is also probably the most effective way to prevent Crimson and Corruption from eventually ruining your world. It involves digging holes. Very big holes.

The system is simple; dig tunnels that entirely encase your Corruption or Crimson biomes before you defeat the Wall of Flesh. Alternatively, you can dig tunnels that surround your base if you keep everything in one location.

You need to dig a surrounding tunnel that is at least three blocks wide, although we recommend going for six, just in case.

Imagine you're drawing a circle around your Corruption or Crimson biome. This trench will prevent the affected blocks from spreading past it.

Remember, vines can grow in tunnels and will spread Corruption once you enter Hardmode. These will grow from underneath the grass blocks.

Even though it's even more time-consuming, you should encase the tunnels in a cheap block, like stone, to prevent vines from growing along the dirt walls. It's extremely frustrating if the vines ruin all the time and effort put into securing your tunnels.

Tips For Digging Quickly

If your world is still in pre-Hardmode, you don't have access to some of the best mining equipment in the game. No super pickaxes, no drills, and no mega-buffs for mining. There are still some things you can use to make this process as smooth and as quick as possible. You can check out these mining methods below.

You can also make these tunnels while already in Hardmode. Make sure you're very quick with the digging, otherwise, you'll be chasing the Evil biome across your world as it spreads.

How To Remove Corruption And Crimson From Your World

If you don't dig tunnels in preparation for Hardmode, you might realize that your world is quickly becoming overrun with Evil biomes.

If you speak with the Dryad, they will tell you how present the evil biome is in your world. This is helpful if you just have a small bit left that needs to be cleared.

Completely Removing Corruption And Crimson

To completely remove Corruption and Crimson from your world, you will need the following:

• The Steampunker NPC
  • This NPC will only appear once you defeat at least one mechanical boss, which appear in Hardmode.

• The Clentanimator
• Green Solution
• A stack of coins

The Clentanimator is a useful tool sold by the Steampunker in Hardmode, though she has to be living in a Jungle biome home. Come prepared, though, it's one of the most expensive items in the game. This tool can be used to both create and destroy biomes.

Green Solution is the ammo you put inside the Clentanimator. When fired it replaces the Evil biome with whatever tile was underneath originally (referred to as "Purity.") Careful, though, this solution will also transform your Jungle into a Glowing Mushroom biome.

The Clentanimator can also be used to remove Hallow. This is done with Green Solution, but you can buy Blue Solution to spread the colorful biome even more.

The best way to try and get rid of all of it (and finally satisfy the Dryad) is to dig a series of vertical tunnels and fire the Clentanimator side to side all the way down. This way you should be able to cover a good portion of the affected area.

Can The Whole World Become Evil?

What happens if the entire world becomes either Crimson of Corrupted? Fortunately, this won't happen naturally.

Both of these evil biomes cannot spread through Hallow, which means that as long as there is Hallow present, your world will have at least two biomes. You can remove Hallow with the Clentanimator though. If you do this without also removing an evil biome, then the world can potentially become overrun.

Once the world is fully evil, you can still remove it with the Clentanimato. This will take a long time, but all hope is not lost.

NEXT: Terraria: Complete Guide And Walkthrough