I have heard many, many conflicting reports on whether or not Crimson will spread in my Ice Biome.
Some people say yes it will, others say that no, it only starts during Hardmode. Still others say it becomes a special kind of biome when it spreads through during Hardmode.
My current base of operations is right next to a snow biome, and I've been thinking of moving it to there to clear out an area for my Arena, but there's a Crimson biome right on the other side of that Ice Biome, and if it's going to spread, I want to be sure my base is safe.
So, does it spread? Does it not? Does it only do it during Hardmode?