Taking some inspiration from the original Planescape Monstrous Compendium entry and building off the 5e air elemental we have the Belker.
Armour Class 15
Hit Points 144 (12d10 +24)
Speed 0 ft., fly 90ft. (hover)
STR 14 (+2) DEX 20 (+5) CON 14 (+2)
INT 10 (+0) WIS 10 (+0) CHA 9 (-1)
Damage Resistances lightning, thunder; bludgeoning, piercing, and slashing from nonmagical weapons
Damage Weaknesses cold, gust of wind acts as a hold spell.
Damage Immunities poison
Condition Immunities exhaustion, grappled, paralyzed, petrified, poisoned, prone, restrained, unconscious
Senses darkvision 60ft., passive Perception 10
Challenge 7 (2,900 XP)
Smoke Form. The elemental 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 belker makes two claw attacks.
Claw. Melee Weapon Attack: +8 to hit, reach 5 ft., one target.
Hit: 14 (2d8 + 5) bludgeoning damage.
Smoke Claws (Recharge 4-6). Each breathing creature in the elemental’s space must make a DC 15 Constitution saving throw or inhale part of the creature. Smoke inside the victim solidifies into a claw and attacks the target from within. On a failure, a target takes 17 (4d8 + 2) piercing damage. On a success the creature spends the turn coughing and choking. A successful save ends the secondary effect.