Blizz

Blizzes are hostile mobs that can be found in cold environments. They are water elementals, just like Blazes are fire elementals. They have a cold and icy look, and produce snowball particles. Blizzes make loud, cold breathing noises, as well as a noise that sounds like ice crackling.

A pack of Blizzes is called a Blizzard.

Behavior

When idle, Blizzes randomly wander around on the ground. When they see a player or a Blaze, they start flying and attacking. Blizzes attack by shooting several icy bolts that can apply a slowness effect in addition to dealing damage. They then wait a few seconds before shooting again.
Blizzes do more damage to entities that are marked 'immune to fire', like most mobs from the Nether.

Spawning

Blizzes can spawn in any cold and/or snowy biomes in the Overworld, in spots with a light level of 8 or darker. They usually spawn in packs of 1-4. Packs of Blizzes are about ten times as rare as packs of mobs like Zombies, Skeletons, Spiders and Creepers. This means packs of Blizzes are about as rare as packs of Endermen.

Note: Blizz spawning is very configurable. This page only describes how Blizzes spawn using the default settings.

Drops

When killed, Blizzes drop 0-3 Snowballs and 0-1 Blizz Rods. They will drop more items if a sword with the Looting enchantment is used.
Blizz Rods can be used to create Blizz Powder, which is a critical ingredient for creating Cryotheum Dust and, ultimately, Gelid Cryotheum.