Throw down Moonbeam and toss a void bulb into it. If you want to get really nasty throw grease or web or both on top of the whole mess.
This works really well on the Githyanki fight. keep the Druid protected and keep tossing Void Bulbs to keep them in the death zone. Rain fire.
Spike growth can also be used instead of Moonbeam, but moonbeam is nice because it doesn't require action to cause damage. However, if you had two druids...then use two moonbeams.
