How to stop corruption spread in terraria?

What Exactly Do the Corruption and the Crimson Refer to?

The Corruption and the Crimson serve as the primary malevolent biomes within your in-game world. In every world, either a Corruption biome or a Crimson biome will come into existence. 

However, there exist a few uncommon world seeds that, upon generation, will give rise to both the Corruption and the Crimson biomes simultaneously. Prior to commencing the generation of a new world, you have the option to decide whether it will initially feature a Corruption biome or a Crimson biome.

The biome you choose will influence the bosses you encounter, such as the Brain of Cthulhu in the Crimson biome and the Eater of Worlds in the Corruption biome. Additionally, this will determine the types of armor and weapons you can craft before transitioning into Hardmode.

How Exactly Does the Expansion of the Corruption and the Crimson Take Place?

Even prior to entering Hardmode, both of these biomes, the Corruption and the Crimson, will gradually expand. They transform adjacent blocks into those of the same biome at an extremely sluggish pace. In the pre-Hardmode stage, their spread is restricted to grass and bushes. Areas that have been converted will feature identical background music, spawn the same kinds of enemies, and support the growth of the same plant species.

Certain specific biomes, such as the Desert or the Snow biome, will exhibit distinctive variations when they are assimilated into either the Corruption or the Crimson. Take, for instance, the Crimson Desert. On its surface, it will give rise to enemies like the Blood Mummies, and beneath the ground, Dark Lamias will spawn. As for the Snow Biome, although it lacks unique enemy spawns, the Ice within it will be transmuted into Red Ice.

Corrupted biomes spread rapidly through soft blocks such as snow and mud. This makes Deserts, Snow Biomes, and the Jungle particularly vulnerable to the swift expansion of corrupted biomes. Consequently, the Jungle biome can quickly become entirely overrun if it is located near an evil biome.

Hardmode Expansion 

In Hardmode, the situation becomes much more intricate. It's not merely that the speed at which the evil biomes spread escalates substantially; rather, the Corruption and the Crimson will now propagate through stone and vines as well. This implies that these malevolent biomes will infiltrate not only the surface areas but also extend their reach deep underground.

The moment you vanquish the Wall of Flesh and transition into Hardmode, the pace at which the biomes spread accelerates significantly. Nevertheless, once you manage to defeat Plantera, this rate of spread diminishes.

This decrease in the spreading rate serves as a safeguard against the biomes taking over your world at an alarmingly rapid pace, especially when you haven't taken measures to fortify or prepare your world beforehand. If you possess the necessary skills and resources, you can prioritize defeating this boss promptly, thereby minimizing the danger of your world being completely overrun by these encroaching biomes.

What is the essence of The Hallow?

The Hallow is a distinct, expansive biome that emerges exclusively upon entering Hardmode. Once you've triumphed over the Wall of Flesh, a section of the evil biome in your game world will transform into the Hallow.

Similar to the Crimson and the Corruption, the Hallow has the tendency to spread. In general, its spreading mechanisms are comparable to those of the other two biomes. Despite its seemingly "adorable" outward appearance, the creatures that inhabit the Hallow still pose a significant threat. Intriguingly, the two malevolent biomes, the Crimson and the Corruption, are unable to spread through the Hallow, and the Hallow, in turn, cannot spread through them. Should any of these biomes come into contact with one another, the process of spreading will halt.

Stopping the Propagation of Biomes in Pre-Hardmode through the Act of Digging Holes

This approach is extremely labor-intensive in terms of time, yet it is likely the most efficient means of safeguarding your world from the eventual devastation caused by the Crimson and the Corruption. It entails the task of excavating holes, specifically, very large ones.

The principle behind this method is straightforward. You need to dig tunnels that completely enclose the Corruption or Crimson biomes within your world before you manage to defeat the Wall of Flesh. As an alternative, if you have concentrated all your important structures and activities in a single area, you can opt to dig tunnels that encircle your base instead.

Bear in mind that once you enter Hardmode, vines can grow in tunnels and will spread the Corruption. These vines will sprout from beneath the grass blocks.

Although it demands even more time, you ought to line the tunnels with an inexpensive block such as stone. This is to prevent vines from growing along the dirt walls. It would be extremely disheartening if the vines undo all the time and effort you've invested in securing the tunnels.

Ways of Removing the Corruption and Crimson from Your Virtual World

If you don't dig tunnels in anticipation of Hardmode, you may find that your world is rapidly becoming overwhelmed by Evil biomes.

Talking to the Dryad will provide you with information about the extent of the evil biome in your world. This can be particularly useful if there's just a small area left that needs to be cleared.

Entirely Eradicating the Corruption and Crimson 

To fully eradicate the Corruption and the Crimson from your game world, the following items and NPC interaction are essential:

The Steampunker NPC:

This particular NPC will make an appearance only after you have successfully defeated at least one of the mechanical bosses. These mechanical bosses are exclusive to the Hardmode stage of the game.

1.The Clentanimator

2.Green Solution

3.A quantity of coins

The Clentanimator is a highly practical tool that can be purchased from the Steampunker during Hardmode. However, it's important to note that the Steampunker must be residing in a home located within the Jungle biome. Be well-prepared, as the Clentanimator ranks among the most costly items in the game. This tool serves a dual purpose; it can be employed to both establish and dismantle biomes.

The Green Solution serves as the ammunition that you load into the Clentanimator. Upon firing the Clentanimator with the Green Solution, it replaces the tiles of the Evil biome (either the Corruption or the Crimson) with the original tiles beneath them, which is known as the state of "Purity." However, exercise caution. When using the Green Solution, it will also convert your Jungle biome into a Glowing Mushroom biome.

Could the whole world be overtaken by evil?

What would transpire if the entire world were to be completely overtaken by either the Crimson or the Corruption? Luckily, this scenario won't occur spontaneously in the normal course of the game.

Neither of these malevolent biomes can spread through the Hallow biome. This implies that as long as there is even a portion of the Hallow biome remaining in your world, there will be at least two distinct biomes present. It is possible to eliminate the Hallow biome using the Clentanimator. However, if you do so without simultaneously removing one of the evil biomes, then there is a real possibility that the evil biome could spread unchecked and overrun the entire world.

Even in the event that the entire world has been fully consumed by evil, it is still feasible to reverse the situation with the Clentanimator. Undoubtedly, this process will be extremely time-consuming, but it's important to note that all is not lost, and there is still a way to restore the world to a better state.