Will Crimson Spread In My Ice Biome?
Solution 1:
Corruption, Hallow, and Crimson can all spread relatively slowly through ice blocks, but not snow blocks.
Solution 2:
Crimson can spread to ice but not to snow, this makes it one of the easier biomes to keep pure since the crimson spreads slowly through ice and not at all through snow. If you are worried just dig a tunnle dividing the two biomes.