You must have a rogue in your raid for this, if shade goes to AOE polymorph the raid have the rogue vanish which removes him from the target for the polymorph, right after shade casts the polymorph have the rogue run up and hit him while he's going to drink. This will cancel not only his drinking but also cancel his AOE pyroblast, not sure if it works with druids also, but may be worth it to test out.