These are the kings of air elementals and one of the more powerful monsters. Their amorphous soft bodies make them largely immune to many spells and damage from all but the most powerful weapons. As neutral creatures, they have no destructive urges, but their low intelligence means that they can easily be tricked.
Oh elementals. You're so difficult to make interesting because you're literally piles of stuff.
Edit: Modelling a goblin in three-dee, y'all.