Terraria is a land of mystery that you can shape, defend, and explore. Sky islands, underground demons, and magical fairies are side by side with biomes like the Crimson, Corruption, and Hallow in a Terraria world.
Every world will contain several randomly generated biomes with unique traits such as enemies, items, and blocks. Certain biomes need to be neutralized before they completely overtake your world.
Upon world generation, the world’s Corruption and Crimson biomes start to spread in every direction. The Hallow biome also follows suit as soon as the Hardmode is unlocked. You must manually take care of them before they swallow your entire world. Certain items and tools can quickly neutralize such biomes.
Maintaining a healthy balance of all forces is better than eliminating the Crimson / Corruption or Hallow biomes. You must farm mobs from such areas to get Souls of Night and Light.
Biome System in Terraria
Much like Minecraft’s terrains, Terraria’s world contains different biomes. They are essentially different types of areas with their unique environments. On the surface layer, you see basic biomes like Forests and Deserts, while the high skies contain the Space biome with near-zero gravity.
The Dungeon biome can also be unlocked after defeating the Skeletron. Next, depending on your world, you see a Corruption or Crimson biome.
These biomes can extend to the underground layer and have a stable expansion rate. This means that they will continue to expand no matter what you do.
Lastly, we have the post-hard mode biome called Hallow, the complete opposite of the Corruption biome. A Terraria world also includes minor biomes such as the Cavern layer, the Mushroom biome, Oceans, etc.
The Corruption / Crimson Biome
You will always get an evil biome from the get-go upon world creation. This hazardous biome will continue spreading naturally, negatively affecting the creatures around it. There are two types of such biomes:
- Corruption
- Crimson
Each world comes with only one such biomes, but the other can be artificially created by gathering seeds from a different world. There is a ½ chance of either biome being generated.
However, the Journey’s End update has enabled players to choose the biome type during world creation. If the biome is not chosen manually, the game will automatically assign either Corruption or Crimson biome to your world based on the probability mentioned above.
An evil biome is highly contagious and is capable of overlapping other biomes. The mix and match provide evil versions of the Desert, Forest, Jungle, Snow, or Ocean Biomes. This can be identified by looking for subtle changes in the biome environment. For example, a corrupted desert will have purple sand blocks instead of yellow.
Corruption Biome
The corruption features a dark purple wasteland, depicting an evil and creepy vibe. Multiple deep tunnels, called chasms in the Corruption biome, allow you to venture into the Underground Corruption, where the Demon Altars are found.
If enough of the world gets corrupted, the affected area will adopt the Corruption theme music, background, and water.
Spread Rate
Inheriting the properties of an evil biome, Corruption automatically spreads from tile to tile. This process happens by having existing Corrupt blocks near susceptible tiles. It will not take longer than a day for that tile to get corrupted.
That said, the spread rate of Corruption varies according to the current game state. It spreads extremely slowly during the Pre-Hardmode but ramps up the spread after the Wall of Flesh has been defeated to unlock Hardmode.
This aggressive spread continues till the player has defeated Plantera. The Corruption spread will gradually calm down to a 50% potency. However, it will still need to be manually controlled as much as possible to reduce the Corruption percentage.
Enemies In a Corruption Biome
The Corruption biome spawns different enemies according to the game’s present state. Therefore, the Hardmode mobs will differ from the Pre-Hardmode variants. The desert biome also tends to spawn unique creatures depending on the time and spawn rate. Here are all the Corrupted enemies that are present in the Corruption Biome.
- Pre-Hardmode
- Eater of Souls
- Corrupt Goldfish
- Devourer
- Eater of Worlds (Boss)
- Hardmode
- Corruptor
- Corrupt Slime
- Slimeling (Spawns from a Corrupt Slime)
- Shadow Slime (Old gen consoles and 3DS versions)
- Slimer
- World Feeder
- Corrupted Desert
- Dark Mummy
- Shadow Mummy (Old gen consoles and 3DS versions)
Corruption: Official Lore
Corruption can be considered a form of cancer caused by the sins of the ones living in Terraria. The vile actions of the evildoers, along with the innate evil present in all living beings, are what fuels Corruption.
Its main purpose is to keep the evil contained by restoring balance to life and then unleashing it all to destroy the balance scale. Ultimately, the world should be nothing more than a lifeless abyss.
Crimson Biome
The Crimson features a creepy aesthetic of a fleshly infection and crimson gore. As the name suggests, the Crimson biome is a bright red biome generated randomly upon world creation. Unlike the dark wasteland aesthetic of the Corruption, Crimson has a much more subtle yet creepy vibe.
Corruption tools are slightly faster with higher stats compared to their Corrupted counterparts. Like the Corruption, the area will adopt Crimson’s theme music, background, and water color if the infestation reaches a certain ratio.
Spread Rate
The Crimson expands and spreads by itself because it is an evil biome. The tiles will be affected by the biome if stayed in range for too long. However, the spread rate of the Crimson is not that great in the early stages of the game. Therefore, you have much time to wander around and get ready.
This changes as soon as the Wall of Flesh is defeated. The fleshly theme of the final Pre-Hardmode boss compliments well with the Crimson. Until the Plantera is defeated in the underground jungle, your world will experience an elevated rate of Crimson spread.
However, it will reset its course to the usual ½ in the latter portion of the game.
Enemies in a Crimson Biome
Much like the Corruption, the Crimson features its own set of Pre-Hardmode and Hardmode Bosses. The mean mechanics of a few of these might differ. However, they work on the same principle as their Corrupted counterparts. That said, here are all the enemies that can be encountered in a Crimson biome.
- Pre-Hardmode
- Blood Crawler
- Vicious Goldfish (Desktop, Console, Mobile, Switch, and tModLoader versions)
- Face Monster
- Crimera
- Brain of Cthulhu (Boss)
- Hardmode
- Herpline
- Crimslime
- Blood Jelly
- Blood Feeder
- Crimsonified Dessert
- Blood Mummy (Desktop, Console, Mobile, and Switch versions)
- Dark Mummy (Old gen consoles, 3DS, and tModLoader versions)
Crimson: Official Lore
The Crimson is a living being that wants to balance the world. The so-called monsters of the Crimson used to worship this being. Ultimately, the being remains unseen while it acts as a hive to inter-connect the entire Terrarian world.
It is safe to say that the Crimstone is that being’s flesh. This theory can be supported by the block’s appearance and the Meat Grinder item is made from these fleshly pieces.
Fun Fact: If you use the seed 05162020 in Terraria 1.4, you’ll have both the Crimson and Corruption biomes in a single world. However, you can also witness Living Trees having Moon Lord Legs with chests that grant Red Potions.
The Hallow Biome
The Hallow is a Hardmode surface biome that spawns when the Wall of Flesh is defeated. A random portion of your world will be infected with this biome, but all that glitters is not gold, and there is a very good reason that might be so.
Pretty or not, the Hallow biome is still one of the three evil biomes present in Terraria. You have a cyan rainbow with rather whimsical-looking creatures one might label as ‘enemies’ after they damage you for your entire health bar.
Once the biome has finished generating, an Underground Hallow biome will follow suit. It can replace parts of the other evil biomes but will be similarly harder to deal with. The Hallow biome can be artificially created with Hallowed Seeds, Holy Water, and Blue Solution.
Fun Fact: The Dryad NPC can accurately tell the player about the percentage of Hallow and Corruption / Crimson in a Terrarian world.
Bosses in the Hallowed Biome
The Hallowed Biome houses two unique bosses that require a certain amount of effort to defeat. However, they are not connected to the main storyline. Therefore, you can take time with them after killing the Moonlord.
They drop decent looks to push you through the difficult segments of the Hardmode. With that said, here are the two Hallowed bosses in Terraria:
Queen Slime
This boss is an early Hardmode and Hallow-themed version of the King Slime that can be called through its spawner item. The Queen slime follows suit in his nonexistent footsteps and drops decent loot for what she’s worth.
She is completely optional to defeat for anyone other than the ones trying to hoard the in-game achievements. You will gain the following achievement from defeating her:
| Icon | Achievement | Text | Description |
 | Just Desserts | “Defeat Queen Slime, giving the coup-de-grace to the sovereign of all that jiggles.” | Defeat the Queen Slime for the first time. |
Empress of Light
The Empress of Light is also an optional boss that can be fought as soon as the Plantera is defeated. She is significantly harder to defeat than the likes of a Queen slime and will typically require you to bring post-golem gear to even have a fighting chance.
Needless to say, she drops high-quality loot including the Terraprisma and Kaleidoscope. However, you will need to kill a Prismatic Lacewing to make her spawn. This critter is so rare that it can only spawn between certain periods. Defeating her will grant you the following achievement:
| Icon | Achievement | Text | Description |
 | Fae Flayer | “Defeat the Empress of Light, responsible for all those flashy lights and glitter.” | Defeat the Empress of Light for the first time. |
Spread Rate
Since it is also an evil biome, the Hallow slowly converts susceptible tiles to their Hallowed counterparts if they are sufficiently near. The speed of Hallow spread remains a high constant in Hardmode and is then reduced to ½ after the Plantera has been defeated.
Hallow can be introduced in a Pre-Hardmode world using Hallowed seeds or Holy water. However, the spread would remain limited and not spawn any Hardmode creatures. If a world is sufficiently Hallowfies, then the background and theme of that area will change.
Enemies in a Hallow Biome
The Hallow biome spawns varied creatures according to the time of the day. This means you won’t be able to face certain creatures whenever you want. However, that does not create a lack of mobs to farm, you might be running for your life in a major portion of the game instead. That said, all the mobs are available in the Hallowed biome.
- Common:
- Pixie
- Unicorn
- During Rain:
- Rainbow Slime
- Night Time:
- Gastropod
- Spectral Gastropod (Old gen consoles and 3DS)
- Hallowed Desert:
- Light Mummy
- Spectra Mummy (Old gen consoles and 3DS)
The Hallowed: Official Lore
An Ancient Spirit of Light has created the Hallow. Once the world’s guardian has been defeated, the light will pour in phenomenally. This extreme overcompensation of purity will convert the energy’s nature to evil.
Therefore, the once pure power known for its ability to cure threats to restore the critical balance of life will instead use everything in its grasp to counterbalance the Crimson / Corruption.
Stopping Evil Biome’s Spread
The evil biomes will spread themselves at constant rates depending on the current phase of the game. They can overlap deserts by spreading through them in Hardmode. The resultant will be a Corrupted / Crimson / Hallow variant of the said biome.
Unique mummy-like enemies will spawn here that are not otherwise accessible in the game. The spread of evil biomes can go out of control if left unchecked for too long. Therefore, it is necessary to in purification activities for the said biomes.
How to Purify Corruption / Crimson
The Corruption and Crimson are near-identical biomes and have similar purification methodologies. Without player efforts, it is only a matter of time before this biome takes over the entire world. However, you still have time until hardmode to handle this spread.
With that said, there are a few easy-to-understand solutions for curing the land of this ailment. Let’s break them down one by one.
Dig 6 Tile Wide Tunnels
A usual strategy seems to be digging 3 tile-wide tunnels to stop the spread of an evil biome. However, doing so does not work in Corruption / Crimson due to the naturally occurring Thorny Bushes. They can propagate the spread of the infection from one block to another.
However, these bushes can only spread the biome for up to 6 blocks. Therefore, increasing the tunnel width to 6 from start to end will most likely do the trick.
You will have to put much effort into locating the spread of underground Corruption / Crimson to implement this strategy.
Use the Clentaminator
The Clentaminator is a gun-like item that can be purchased from the Steampunker NPC for 2 Platinum. As long as you have the money to purchase its ammo, nothing can stop you from purifying the outskirts of Terraria. Simply purchase a ton of Green Solution from the Steampunker and load her up.
Head to the infected area and aim the Clentaminator on large patches of the Corruption / Crimson. Most players prefer keeping some of the biomes to reap their benefits. However, you can artificially plant it by buying Corrupted / Crimson seeds from the NPCs.
Plant Another Biome
Since spreading biomes are relentless in their chase, letting them contest with each other is better. Ideally, you can plant the Hallow biome in the Corruption / Crimson biome to let them duke it out with one another. While this method is relatively low effort, it does the job for a significant portion of the game.
However, you will need to monitor the spreads from time to time. If an evil biome manages to uproot the other, you will have a much more out-of-control spread. Therefore, it is recommended to keep them in check wherever possible.
How to Purify The Hallow
After the Wall of Flesh has been defeated, the Hallow will be generated. It works similarly to a Crimson / Corruption biome and spreads aggressively until the Plantera has been defeated. Much of the above-mentioned strategies can work just as well for the Hallow, albeit with minor changes.
You will need to spend considerable effort to remove a biome from the face of your world, but it should be much easier to contain it. With that said, let’s get to purifying the Hallow!
Dig 3 Tile Wide Tunnels
Unlike the Thorny bushes and water bodies in the Crimson / Corruption biome, the crimson can only be propagated through solid blocks. Therefore, you don’t need that wide of a tunnel. You must locate the Hallowed blocks and create three tile wide spaces among them.
As mentioned, it is a good strategy to contain the Hallow from spreading, but it’s a time-consuming one. This hits harder when you have yet to explore most of the map, as there is no better way of locating the underground hollow otherwise.
Using the Green Solution
The Clentaminator’s Green Solution ammo can purify any kind of evil biome. It also converts the Glowing Mushroom biome to a regular jungle. However, this solution can only be bought from the Steampunker in locations other than the Halo. This solution can be bought for 25 silver leading to a costly removal of infections.
Nonetheless, the Clentaminator is the fastest method to eliminate the Hallow biome. Therefore, the price is worth it in most cases.
Using Throwables
Sprinkling Vile Powder or throwing Unholy Water is another great way of removing the Hallow biome. However, you will need to have an Alchemy Station at hand to craft the mentioned items successfully. With that said, here are the recipes for components needed to craft Vicious / Vile Powder and Unholy Water:
Unholy Water:
Here is the recipe for Unholy Water along with its components:
| Result | Ingredients | Crafting Station |
 Bottled Water (10) | ||
 Unholy Water (10) (     ) |  Ebonsand Block | By Hand |
 Corrupt Seeds |
| Result | Ingredients | Crafting Station |
 Bottled Water |  Bottle |  Water or  Sink |
Vicious / Vile Powder:
Here is the recipe for Vicious / Vile Powder along with its components:
| Result | Ingredients | Crafting Station |
 Vicious Powder (5) |  Vicious Mushroom |  Placed Bottle / |
 Vile Powder (5) |  Vile Mushroom |  Alchemy Table |
Biome Requirements For Corruption, Crimson, and Hallow
To artificially create such biomes, you must know the minimum requirements. The Corruption and Crimson have near-similar requirements, while the Hallow needs lesser attention care. A planted biome will spread on its own. Therefore, most of the mentioned requirements will automatically be fulfilled.
Corruption / Crimson Biome
The Corruption / Crimson biome prerequisites include at least 300 / 200 blocks of the Corrupted / Crimson items. 40 / 80 blocks increase the Corruptions biome’s requirements for every Sunflower present. The presence of a Hallow block can witness a similar case as each one increases the requirement by 1.
Hallow Biome
Unlike Corruption / Crimson, you only need 125 / 100 blocks of Hallowed tiles. This requirement is increased by 1 for every Corruption and Crimson block placed.
Removing the Hallow, Corruption, and Crimson in the area can cost you a lot of time. However, items like the Clentaminator can reduce this workload by a significant amount. Therefore, getting rid of such biomes can cost significant money if not time.