Did it relatively easily as a 25 pally......things that worked for me:

(1) Conserve mana.
(2) Ruul is tough, so let him fight as well.
(3) Towards the end I got ahead to try to clear, but that was a mistake as you don't know exactly when the 3 mobs spawn.  My suggestion is to only kill the mobs really close to Ruul, so you don't get a 4 pull.
(4) Don't waste time looting...you will drop out of combat a couple of times, drink and eat as soon and as long as possible....he moves slowly so you can let him get a few paces ahead while you are eating.

Good luck.