1 mage can kite the whole room of bombozombies with imp blizzard just going around the ring, and jumping down / back up if needed. I was doing this pre TBC whilst farming the leather working mat that popped down there in the basement. Have mage positioned around the corner, puller runs in and aggros zombies and pulls them back to the door, let loose with bliz and just start trucking around the top ring there. You can hop down to buy yourself time for a heal if something goes awry.