Multiattack

The polyp makes two melee attacks.

Tentacle

Melee Weapon Attack: +9 to hit, reach 15 ft., one target. Hit: 15 (3d6 + 5) bludgeoning damage. If the target is a Large or smaller creature, it is grappled (escape DC 17). Until this grapple ends, the target is restrained and is not affected by the flying polyp's Aura of Wind. The flying polyp can grapple up to two creatures at one time.

Bite

Melee Weapon Attack: +9 to hit, reach 5 ft., one target grappled by the polyp. Hit: 18 (3d8 + 5) piercing damage.

Cyclone (Recharge 5-6)

Each creature within 30 feet of the polyp must make a DC 17 Strength saving throw. On a failure, a creature takes 27 (5d10) bludgeoning damage and is knocked prone. On a success, a creature takes half the damage but isn't knocked prone.

Etherealness

The flying polyp magically enters the Ethereal Plane from the Material Plane, or vice versa.