Use lesser health poultices on cooldown, on whatever character he's beating on.
Normal/Greater/Potent health poultices are not on a shared cooldown with lesser.
Save Group Heal for after mass pull.
Use regeneration early, if you want, but try to save your single target Heal spell for when he uses pull on his current target, because you said target can not use a poultice while on the floor.
Make sure the revenant is not immune to the type of damage coming from your mages' staves; keep a backup staff with a different element, even if it's a shitty staff, because some damage is better than none.
With all of that in mind, Revenants are still bullshit, because they resist a lot including the -resist hex. This meant no paralyze or captivating song, which often meant no backstab (WHAT IS A WARRIOR TANK I HEAR THOSE ARE FOR FAGS). I think the ones I fought were fucking frost immune, so there was no frozen status from cone of cold, either.
P.S. You can't spam potions in WoW. You can in Diablo (and most clones). The GOASTS thing is in reference to people dying to ghosts spawning from dead mobs in Naxxramas (and Sunken Temple) though.