Air Form. The Aer can enter a hostile creature's space and stop there. It can move through a space as narrow as 1 inch wide without squeezing.

Multiattack. The Aer makes three slam attacks.
Slam. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 14 (2d8 + 5) bludgeoning damage.
Whirlwind (Recharge 4–6). Each creature in the Aer's space must make a DC 15 Strength saving throw. On a failure, a target takes 23 (4d8 + 5) bludgeoning damage and is flung up 30 feet away from the Aer in a random direction and knocked prone. If a thrown target strikes an object, such as a wall or floor, the target takes 3 (1d6) bludgeoning damage for every 10 feet it was thrown. If the target is thrown at another creature, that creature must succeed on a DC 15 Dexterity saving throw or take the same damage and be knocked prone.
If the saving throw is successful, the target takes half the bludgeoning damage and isn't flung away or knocked prone.