Air Form. The stalker can enter an enemy's space and stop there. It can move through a space as narrow as 1 inch without expending extra movement to do so.
Invisibility. The stalker has the Invisible condition.
Multiattack. The stalker makes three Wind Swipe attacks. It can replace one attack with a use of Vortex.
Wind Swipe. Melee Attack Roll: +7, reach 5 ft. Hit: 11 (2d6 + 4) Force damage.
Vortex. Constitution Saving Throw: DC 14, one Large or smaller creature in the stalker's space. Failure: 7 (1d8 + 3) Thunder damage, and the target has the Grappled condition (escape DC 13). Until the grapple ends, the target can't cast spells with a Verbal component and takes 7 (2d6) Thunder damage at the start of each of the stalker's turns.