The evil biomes of the Corruption and Crimson are some of the scariest parts of Terraria. They are critical to farm for materials at all portions of the game, but in Hardmode they can begin to spread. If you’re not careful, these parts of the map can slowly overwhelm the entire map! If you’re wanting to stop the evil Crimson and Corruption biomes from spreading any further, there are a few things you can do. This guide will go over the best possible ways to do so!
How to Stop Corruption in Terraria
Early on, you can stop the Terraria Corruption (or Crimson) by digging a 3 tile wide trench on either side of the biome. This trench, if lined with wood or other non-corruptible tiles, is your quarantine zone, and will prevent further spread. In Hardmode, you can use the Clentaminator to cure blocks that have been corrupted. You can also begin planting Hallowed Seeds around effected areas to slow the spread aboveground.
There is not much a player can do to slow the spread of the Evil Biomes before Hardmode. Building a 3-tile wide trench is your best option to ensure that the area doesn’t move. However, this does not stop the Hardmode biome spawns from just screwing up your plan! You’ll need to be ready to build multiple 3-tile trenches in the future. Killing the Wall of Flesh will spawn even more evil for you to clean, after all!
Evil Biomes, like the Corruption and Crimson, spread fastest above ground. Using Sunflowers and other surface-world grass tiles that can’t be corrupted can be a massive help early on.
Once you reach Hardmode, make sure you’re fully geared before trying to tackle the anti-spread task. You can do this by breaking Altars, but if you’re unlucky, this may advance the spread even more. Holy water can be an ineffective emergency solution. Sunflowers and other incorruptible grass tiles (like Wood) can stall the spread on the surface of the world.
The most foolproof option is the Steampunker’s Clentaminator. This NPC requires the Players to kill one Mechanical boss. This incredible spray can quickly and effectively clean many tiles. Make sure you have the correct Solution and have a Quarantine plan to prevent the tiles from being re-corrupted. You can replace the Corruption or Crimson with Hallow tiles, for instance, since those can’t be corrupted.