Kill Priest then Warlock. The advent of Pain Suppression for Disc Priests has caused a decline in this comp but this is usually a very difficult fight when you do see it. 99% of the time, they will try to kill your Warrior. It is absolutely crucial that the Druid has 3xLifebloom/Rejuv on the Warrior, Nature's Swiftness queued up, and be ready to LoS fear and silence. The warrior should pop Battlemasters trinket at about 70% HP, trinket any Blackout procs, and Pummel any shadow spells the Priest casts. It is imperative that you get the priest dead ASAP. Intervene back to you druid if you get low. Once the priest is dead the fight is trivial.