Tiamox

Thiamox is an atta boss required for the Thunderhead Targets of Oppertunity and is found found at Map coordinates -833, 316, usually stationary near the cliff just behind a ridge.
Thiamox is also part of the quest "Up and Atta them" for which he isn't to be killed, but trained over 5 way points in his vicinity, he can be safely killed after passing the last way point.