At hardmode it stands to reason that it still spreads as before but it s unclear whether it can now spread to rock due to the 3 tile rule.
Can corruption spread through granite.
Only the following blocks can spread the corruption crimson.
Grass stone sand and ice.
Now has a underground theme.
Recently as of 1 3 the corruption can now spread through the jungle biome.
From my experience the corruption crimson and hallow can spread to any corruptible block up to 3 blocks away so a three block gap should be sufficient to stop spread.
Anything else is fair game.
This allows it to spread into the cavern layer.
Now has own specific background.
Corruption and crimson can convert mud to dirt.
The list of blocks that can be converted is much shorter.
An artificial corruption biome now only requires 200 ebonstone blocks instead of 500 blocks.
The corruption biome can t spread through hallow and does not sourness the underground and carven enemies.
While crimson plants and vicious mushrooms are able to act as source tiles their corruption equivalents corrupt plants and vile mushrooms are not.
Plants trees and vines can indirectly be converted when the blocks they re on get converted.
The monsters that you find in this biome at any time of day are relatively stable and acts as an excellent reason to avoid corruption at the beginning of the game.
In pre hardmode the three biomes can only spread in a very limited way.
It wouldn t be a bad idea to.
Also most monsters appear to be worms as well as the boss.
This happens by the corruption slowly transforming the mud blocks into dirt and stone so the biome can spread through grass and stone blocks.
In practice it doesn t matter as the spread of corruption through stone and other blocks is faster than the growth of the bushes.
Note the inconsistency here.
In addition to this remember that the corruption and hallow can jump three blocks to reach another block and continue spreading.
The only spreading tiles are corrupt crimson and hallowed grass and corruption and crimson thorny.
Absolutely everything else is neutral and won t convert either way.
Dirt with grass on it.
And mud but that can only be corrupted and not hallowed.
Mud will be gradually converted to dirt stone.
Crimson corruption will turn the mud to dirt and transform any sand or stone but it won t affect the mushroom grass itself.
No blocks will block the spread of corruption crimson.
Corruption spreads through sand and stone and will slowly turn mud to dirt after the wall of flesh is destroyed.
Granite wood even stone brick any of these will work.
I e putting an uncorruptable snow block or two in between an ebostone block and a regular stone block will still result in the stone block.
Hallow will affect sand and stone but leaves the mud alone and again won t change the grass.
Added to the game.
If you are blocking surface crimson corruption you should fill the gap up with non corruptible blocks only from the underground crimson corruption the music will change.