Modified air elemental using 3.5 edition template/example from Dragon #347.
Armour Class 15
Hit Points 90 (12d10 +24)
Speed 0 ft., fly 90ft. (hover)
STR 14 (+2) DEX 20 (+5) CON 14 (+2)
INT 6 (-2) WIS 10 (+0) CHA 6 (-2)
Damage Resistances lightning, thunder; bludgeoning, piercing, and slashing from nonmagical weapons
Damage Immunities poison
Condition Immunities exhaustion, grappled, paralyzed, petrified, poisoned, prone, restrained, unconscious
Senses darkvision 60ft., passive Perception 10
Challenge 5 (1,800 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 elemental makes two slam attacks.
Slam. 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 13 Constitution saving throw. On a failure, a target takes 15 (3d8 + 2) piercing damage as the semi-vaporous smoke forms into claws within their lungs and begins to rend them. They also spend the turn coughing and choking. A successful save ends the effect.