I had reported this when Eye of the Storm came out but there've been no changes to them since.
Really hoping this gets changed, they seem really unfinished.
They're immune to freezing, fire, and sleep...
This includes the Dragon scale armor, the chilled amulet, the sleep sacks, and the panflute.
They also phase through solid walls.
It seems like their attack cuts off too early, they do damage before the full animation plays too.
Activate the Moon storm, wait for birds to spawn. Try to freeze/sleep/alight them. Weep in agony.