Rotting Wind

Air Form. The rotting wind can enter a hostile creature's space and stop there. It can move through a space as narrow as 1 inch wide without squeezing.

Invisibility. The rotting wind is invisible.

Poisonous Aura. The rotting wind radiates an aura of poison and decay that slowly pollutes the area within 30 feet of it. Each hour the rotting wind stays in a place, nonmagical plants in the aura begin to wither, and water in the aura becomes poisoned. Nonmagical plants in the aura for 24 hours die. A creature that drinks water poisoned by the aura must succeed on a DC 14 Constitution saving throw or contract the tomb rot disease (see the Tomb Rot trait). Creatures immune to the poisoned condition are immune to this disease.

Tomb Rot. A creature infested with this disease manifests symptoms 1d4 days after infection, which include muscle weakness and rotten-smelling breath as its body rots from the inside out. Until the disease is cured, at the end of each long rest, the infected creature must succeed on a DC 14 Constitution saving throw or take 10 (3d6) necrotic damage and suffer one level of exhaustion. This exhaustion lasts until the creature finishes a long rest after the disease is cured. A creature that succeeds on two saving throws recovers from the disease.

Undead Nature. The rotting wind doesn't require air, food, drink, or sleep.

Multiattack. The rotting wind makes two Wind of Decay attacks. If both attacks hit one creature, the target must succeed on a DC 14 Constitution saving throw or contract the tomb rot disease (see the Tomb Rot trait).

Wind of Decay. Melee Weapon Attack: +8 to hit, reach 0 ft., one target in the rotting wind's space. Hit: 12 (2d6 + 5) bludgeoning damage plus 10 (3d6) necrotic damage.