"This guy is like Team Rocket, Jinnai, Ranma, and any other eccentric ham that was ever a sarcastic jerk to someone rolled into one evil keeper." (comment on Mukrezar)
Mukrezar was a Keeper renowned for accomplishing what was previously unthinkable - conquering Avatar Island. After he accomplished this he plundered the land for ressources until nothing was left. Soon enough his minions rebelled and the whole shtick went under in a glory of violent cannibalism, with Mukrezar being among its victims.
This feat showed his talents as a tactician as well as his lack in long-term planning.