Don't really know much about Zovaal since WoW's lore is obviously utter shit, but I was watching a video that reminded me of him and I did a quick google to see what exactly he was now that we know more about him (I quit near the start of SL)
It's my understanding he's one of the members of the Pantheon of Death. Now, Sargeras is the big bad of the Pantheon of Order.
Who's stronger?