been using pandaren water spirit, stitched pup (geyser, whirlpool, howl, bite on legendary) and hyjal wisp because the majority of the backline pets seem to be flying, so arcane blast deals with them and wish deals with the 50% damage bonus they have, usually get it in about 21rounds, a little slow ...

my levelling pet died the first time i tried to tyraels omnislash (level pet had 730hp) but was ok the second go around, i think i just got unlucky or messed up a turn

i went with the tried and true unborn val'kyr, pandaren water spirit, chrominius method start with val'kyr: curse of doom, unholy ascension switch to water spirit: geyser, whirlpool switch to chrominius: howl, surge of power should be dead at this point, won with this a few times to get further alon...