Do Walls Spread Corruption in Terraria? The Definitive Guide
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The short answer is: No, walls themselves do not directly spread Corruption, Crimson, or Hallow in Terraria. However, the situation is more nuanced than a simple yes or no. While the background walls you see might visually change to reflect the biome around them, they do not inherently carry the spread. The conversion of walls you observe is a visual effect that occurs within an approximate 8-block radius of converted blocks. This means that a wall might look corrupted, but it will not be the source of new biome spread. Understanding this distinction is key to effectively managing biome spread in your Terraria world.
The Misconception: Visual Changes
It’s easy to fall into the trap of thinking walls are spreading corruption when you see them transform. When Corruption, Crimson, or Hallow take hold, you’ll notice certain natural walls changing their appearance. For instance:
- Mottled Stone Walls become Corrupt Pustule Walls
- Fractured Stone Walls become Corrupt Tendril Walls
- Worn Stone Walls become Corrupt Growth Walls
- Stalactite Stone Walls become Corrupt Mass Walls
These visual changes are simply the game’s way of reflecting the surrounding environment. These converted wall types, despite their appearance, will not cause further biome spread.
What Does Spread Corruption?
While walls aren’t the culprit, several factors contribute to the spread of Corruption, Crimson, and Hallow:
- Convertible Blocks: The primary means of spread is through convertible blocks, such as grass, stone, and sand. When these blocks are corrupted, they can convert adjacent convertible blocks.
- Vines and Thorns: These can extend from corrupted blocks and convert blocks they touch, often reaching through gaps you might have intended as safe zones.
- Corrupt Seeds: These items can be used to manually spread Corruption on grass, turning it into a corrupted version.
- Unholy Water: This liquid can instantly corrupt grass, stone, and other convertible blocks it touches.
- The Clentaminator: This tool, using Purple Solution (for Corruption) or Red Solution (for Crimson), is a powerful way to both spread and purify biomes. However, it can inadvertently spread the relevant biome if used improperly on unsafe walls.
Placed Walls vs. Natural Walls
There’s an important distinction between naturally generated walls and walls placed by the player. Player-placed walls are generally considered “safe” meaning that, if placed after being mined by the player, they cannot be corrupted and, most importantly, do not spread biome conversion. These walls effectively act as a barrier against biome spread. However, there are exceptions. For example:
- Stone Walls can be converted to unsafe Ebonstone Walls by the Clentaminator (using Purple Solution) or Unholy Water. These unsafe walls can then contribute to the spread of Corruption.
- Similar to above, Grass, Flower, and Jungle Walls can be converted to unsafe Crimson Grass Walls by Red Solution or Blood Water, and can then spread the Crimson.
How to Control Biome Spread
Knowing that walls don’t spread biomes opens up a number of strategic options for containment:
- Barriers: Creating 3-tile wide trenches on the edges of biomes, lined with non-corruptible materials like wood or clay, will prevent further spread.
- Non-Convertible Materials: Using materials such as clay, bricks, silt, or ash for construction can prevent corruption from spreading.
- Purification: The Clentaminator with Green Solution is crucial for purifying large areas, removing unwanted Corruption, Crimson, or Hallow.
- Sunflowers: These plants prevent corruption in the two tiles directly underneath them and also decrease an area’s total Corruption rating by 5 tiles.
Frequently Asked Questions (FAQs)
1. Can Corruption spread through placed walls?
No, generally speaking, player-placed walls are “safe” and will not spread Corruption, Crimson, or Hallow. However, as mentioned, certain wall types can be converted to unsafe versions by using the Clentaminator with the correct solution, and those unsafe walls can spread corruption.
2. What blocks don’t spread Corruption?
Clay, bricks, silt, and ash are resistant to Corruption, Crimson, and Hallow. You can utilize these materials to create effective barriers. Also, most player placed walls will not spread corruption.
3. Does breaking Demon Altars spread Corruption?
Yes, each time you break a Demon or Crimson Altar, there’s a 2/3 chance that a single random Stone Block in the Cavern layer will be converted to Ebonstone/Crimstone or Pearlstone, facilitating the spread of Underground Corruption/Crimson or Hallow.
4. Can Gray Bricks be corrupted?
Gray Brick is a basic brick resistant to the spread of Corruption, Crimson, and Hallow.
5. Do sunflowers stop Corruption?
Yes, sunflowers prevent the two tiles directly underneath them from being corrupted and reduce the total corruption rating of the area around them.
6. Is it possible to have 0 Corruption in Terraria?
Yes, it’s possible to completely purify your world, but it can be a time-consuming process, especially in Hardmode where biome spread is more aggressive.
7. Can Crimson spread by walls?
Technically, unsafe Crimson Grass Walls can spread the Crimson, but only after having been converted using Blood Water or the Clentaminator with Red Solution. Regular walls, even if visually converted, won’t spread the Crimson.
8. Are dirt walls safe in Terraria?
Dirt Walls that are naturally generated are considered unsafe and can be converted, however they will not spread the corruption or crimson. But, like most walls, if mined by the player and then re-placed, they are considered safe and won’t spread corruption.
9. Can Hallow take over Crimson?
Hallow can convert Crimson and Corruption into grass blocks, but it cannot convert blocks already claimed by an evil biome (i.e., stone or sand already turned to ebonstone or crimstone). This can lead to intertwined areas of Hallow and evil biomes.
10. Is the Hallow good or bad?
The Hallow is generally considered “good” as it does not impede NPCs from moving in and can counteract the spread of evil biomes.
11. Can NPCs live in the Hallow?
Yes, unlike in Corruption/Crimson biomes, NPCs can live in the Hallow without any issues.
12. Can Mud be corrupted in Terraria?
Yes, Mud has its own corrupt, crimson, and hallowed variants, and it will not convert into Dirt.
13. Do altars count as corruption?
No, Demon Altars or Crimson Altars and the ores they generate do not count toward your world’s corruption percentage.
14. Can corruption spread through the jungle?
Yes, in Hardmode, the Jungle can be overtaken by Corruption/Crimson, making it more challenging to access Jungle resources.
15. Do you need to break walls to stop Corruption?
No, you generally do not need to break walls to stop corruption as walls will not spread the biome. However, some walls can be transformed by player activity and are capable of spreading the corruption, so those would need to be dealt with. If a wall is unsafe, it can spread it.
By understanding these nuances, you’ll be much better equipped to manage your Terraria world and maintain the desired balance of biomes. Remember, the key is to understand the difference between the visual appearance of corrupted walls and the actual mechanics of biome spread. Good luck, and happy gaming!