How do the Biomes work, anyway?

[Lucky Thirteen]

Before I trigger the Hardmode, I'd like to understand the mechanics behind Biomes, specifically how does underground hallow/corruption affect the surface.


The theory is that you need to have at least 250(?) blocks of the particular kind, but how does it actually work?

Let's say I want to let the Corruption spread through most of my Snow biome, but I want to keep a bit of the biome intact so a NPC can live there. What do I need to do?
Do I need to dig a tunnel running all the way to hell, or would simply making a barrier around a piece of snowy/icy land (not too deep) be sufficient?


Also, underground hallowed/corrupted snow biome - does it still spawn the "snow" monsters?

[KittyVonPaws]

yes it dos

[Nymbo]

Well once you triger hardmode a random part of the world will become The Hallow Biome. If it takes over a snow biome, it will make sorta like a hybrid biome. Half-Snow Half-Hallow. But to stop Hallow, Corruption, or Crimson, Talk to the dryad, or the steampunker.

[Cheffy]

İlk olarak Lucky Thirteen tarafından gönderildi:

Before I trigger the Hardmode, I'd like to understand the mechanics behind Biomes, specifically how does underground hallow/corruption affect the surface.


The theory is that you need to have at least 250(?) blocks of the particular kind, but how does it actually work?

Let's say I want to let the Corruption spread through most of my Snow biome, but I want to keep a bit of the biome intact so a NPC can live there. What do I need to do?
Do I need to dig a tunnel running all the way to hell, or would simply making a barrier around a piece of snowy/icy land (not too deep) be sufficient?


Also, underground hallowed/corrupted snow biome - does it still spawn the "snow" monsters?

To answer this question in detail, as soon as you kill the WoF, it should show a message saying the souls of the light and dark have been released, a random part of the world (even corruption) will become hallow and spawn hallow themed monsters, the underground hallow does not affect the surface as it is a very different biome, same goes with the underground corruption. if you want to stop corruption/hallow spreading you need to make a 3x3 block of wood or snow, this will grant that the hallow or corruption wont go past it. i believe underground hollow or corruption will still spawn snow mosnters (not 100% sure). hope i helped :)

[Celator]

The number of blocks it takes to make a biome varies depending on the biome, and I too have been trying to find out the numbers on this to help make some key farms. What I've discovered is the following:

-Hallowed requires 100 pearlstone blocks, unless there is Corruption or Crimson nearby, in which case it will require more.
-Corruption and Crimson both require 200 blocks each of Ebonstone or Crimstone. (I've personally confirmed this.)
-Jungle requires 150 mud blocks with jungle grass on them.
-Meteor requires 50 meteorite blocks. (This has been thoroughly confirmed by just about everyone.)
-I don't know how many blocks snow requires, but both snow and ice blocks seem to work.

The game will decide you are in a certain biome when the correct number of blocks is within a certain range of your character, about a 250 block radius. When there are enough blocks nearby to place you in a biome the background will change to it and its music will start to play, and enemies from that biome will start spawning and you'll be able to get biome-specific drops like keys and souls. It is possible to be in more than one biome at the same time and receive drops for all those biomes, though the background and music will only be for one of the biomes (there seems to be a set priority to determine this).

As for how to isolate the Hallow and Corruption, they can only spread up to three blocks away, so if you just mine a three-block-wide tunnel around the biome it should stop it from spreading. However, for your situation this may not be all that useful, since the generation of the underground Hallow and Corruption happens instantaneously and is not affected by the normal growth rules for those biomes. Even if you isolate the Corruption in pre-hardmode, once you beat WoF, it'll generate the Underground Corruption as it normally would anyway.

Corrupted and Crimson snow biomes will still spawn snow monsters, in fact I haven't ever seen a Corruption or Crimson monster spawn in a hybrid snow biome. However, I believe that corrupted/crimsoned ice will spawn Corruption/Crimson Key Molds rather than Frozen ones, so you may want to keep some of your ice biome for more than just NPCs.

[Lucky Thirteen]

Thanks for your answers, everyone

Over8001:
That is exactly what I wanted to know, it's gonna help me a lot. Thank you very much

[chɐos_]

YEA man you are best :D

[Celator]

No problem. Note that aside from the ones I said I'd personally verified, I'm not absolutely sure about any of those block requirement figures, so take them with a grain of salt. If anyone can vouch for any of the others it'd be appreciated.