Frosts will be a new hostile mob which will spawn in mountain biome will occasional speed buff and has 3 types of attack:
1.If get hit by these during daytime can give you slowness level 2 but if they hit during night there is 5% chance of getting inflicted by blindness for 3 seconds and will normally inflict you with nausea .
2. Their second ability is to craft simple tools and crafting tables (as their most of the body is frozen it slows brain decay and have some abilities similar to player) but they can't craft tools higher than wood (as it would be too OP)
3. Their third and last ability is that they can sometimes pull out stuff from your inventory to get materials for crafting (this can only happen when they hit you and has only 20% chance of happening)
Possible drops:Besides rotten flesh it would drop a very rare drop which is same as killing either skeleton for either skeleton heads known as frozen skin which can be brewed into a portion of camouflage which reduces the chance of a specific mob identifying the player .Eg:If you want a portion for camouflaging among creepers you need to add a creeper head into the brewing slot with portion of camouflage similarly to get portion of camouflage for zombies/husk(rotten flesh),ghast(gast tear),endermen (eye of ender) their respective drops will be required.