Chainrasp

Ethereal Sight. The chainrasp can see 60 feet into the Ethereal Plane when it is on the Material Plane, and vice versa.

Incorporeal Movement. The chainrasp can move through other creatures and objects as if they were difficult terrain. It takes 5 (1d10) force damage if it ends its turn inside an object.

Etherealness. The chainrasp exists in the Ethereal Plane. It is visible on the Material Plane while it is in the Border Ethereal, yet it can't be wholly affected by anything on the other plane. When targetted by a being in the Ethereal Plane the chainrasp is treated as having no resistances or immunities.

Withering Weapon. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 7 (1d6 + 3) slashing damage and 10 (2d6 + 3) necrotic damage.

Gaze of the Damned. Each non-undead creature within 60 feet of the chainrasp that can see it must succeed on a DC 15 Wisdom saving throw or be frightened for 1 minute. If the save fails by 5 or more, the target also ages 1d4 × 10 years. A frightened target can repeat the saving throw at the end of each of its turns, ending the frightened condition on itself on a success. If a target's saving throw is successful or the effect ends for it, the target is immune to this chainrasps's gaze of the damned for the next 24 hours. The aging effect can be reversed with a greater restoration spell, but only within 24 hours of it occurring.