Alpha Yeti

The Alpha Yeti is a mob added by Twilight Forest. It must be defeated to access the glacier biome. It is immune to bows. It can throw ice blocks that can slow players down. After a couple of sword strikes, the yeti starts to flail about, knocking all players within range back and damaging them.

In Minecraft 1.7.10, when the Alpha Yeti flails about he is vulnerable to and can take damage from a Bow (later versions untested). It is not known if this is a bug.