Multiattack

Two Slams or one Slam and one Constrict.

Slam

Melee Weapon Attack: +8 to hit, 5 ft., one target, 14 (2d8+5) bludgeoning damage + 7 (2d6) poison.

Constrict

Melee Weapon Attack: +8 to hit, 5 ft., one target, 14 (2d8+5) bludgeoning damage and target is grappled (escape DC 15). Until this grapple ends target is restrained and soot can't Constrict another target.

Engulfing Sootstorm (Recharge 4-6)

Spins violently in place spreading out tendrils of thick poisonous ash. Each creature within 20' of it:21 (6d6) poison and speed is halved (DC 15 Dex half damage and speed isn't reduced). Speed reduction lasts until creature uses action cleaning off the ash.