Freezer

An undead mob that appears in the mountains, giving the player a freezing effect.
This mob is unaffected by sunlight and does not burn.
However, it is vulnerable to heat, so if you are in a hot nether or arid biome (desert, savanna, etc.), the heat will damage it like a snow golem.
If you have any other good ideas, let us know in the comments.
Thank you for taking a look at my thoughts.