I have been running a mordor orc army, which includes a mumak as an ally. In the last tourney it performed spectacularly or did nothing. Of my four opponents only two were evil armys and the mumak ground the first one into the dust, the second simply avoided combat. Against a galadrim elf army it lasted three turn before it was pincushioned. And versus a dwarf / army of the dead combo the artillery killed it pretty quick. So as my opponents know I have one and its a large part of my army I am considering swapping with a unit of cataphracts.