Multiattack. The ushabti makes two Nabboot attacks.

Nabboot. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 12 (2d6 + 5) bludgeoning damage plus 13 (3d8) necrotic damage. If the target is a creature, it must succeed on a DC 16 Constitution saving throw or be cursed with tomb taint. The cursed target's speed is halved, and its hp maximum decreases by 3 (1d6) for every 24 hours that elapse. If the curse reduces the target's hp maximum to 0, the target dies, and its body turns to dust. The curse lasts until removed by the remove curse spell or comparable magic.

Serpentine Armlets (1/Day). The ushabti commands its armlets to drop to the floor and transform into two giant, poisonous snakes. The snakes act as allies of the ushabti and obey its spoken commands. The snakes remain for 1 hour, until the ushabti dies, or until the ushabti dismisses one or both of them as a bonus action. When the snakes disappear, they become wisps of smoke and reform as armlets around the ushabti's arms.