Multiattack

The plague spirit makes three attacks: one with its enfeebling touch and two with its censer.

Censer

Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 13 (2d8 + 4) bludgeoning damage plus 7 (2d6) necrotic damage.

Enfeebling Touch

Melee Weapon Attack: +8 to hit, reach 5 ft., one creature. Hit: 14 (4d6) necrotic damage, and the target's Strength score is reduced by 1d6. The target dies if this reduces its Strength to 0. Otherwise, the reduction lasts until the target finishes a short or long rest.

Dance of Death (Recharge 5-6)

The plague spirit dances and twirls its censer. Each creature within 20 feet of the plague spirit that can see it must make a DC 16 Constitution saving throw. On a failure, a creature takes 28 (8d6) necrotic damage and is frightened for 1 minute. On a success, a creature takes half the damage and isn't frightened. A frightened creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.