Shedded Husk

Wonderous Shield. The shedded husk has a maximum of 1 hit point and cannot benefit from any magic or spells that would raise its hit point maximum. The shedded husk is immune to all damage except Fire, Necrotic, and Radiant.

Static. The body of the shedded husk remains motionless and unmoving. All creatures have disadvantage on insight checks against the shedded husk.

Spectral Claw. Melee Weapon Attack: +4 to hit, reach 5ft., 1 target. Hit: 19 (4d6 + 5) necrotic damage. 

Endless Void. The shedded husk turns to expose the hole in the back of its carapace. Each non-undead creatures within 60 feet of the shedded husk must succeed on a DC 15 wisdom saving throw or be frightened for 1 minute. If the target fails by 5 or more, the target must roll on the temporary madness table and be placed under its effect. 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 shedded husk's Endless Void for the next 24 hours.

Curse. The shedded husk sends forth necrotic energy to infect nearby creatures. Each non-undead creature within 10 feet of the shedded husk must make on a DC 16 constitution saving throw. On a fail, a creature's current hit points and hit point maximum is reduced by half. A creature's hit point maximum is restored after completing a long rest or by the Greater Restoration spell. On a success, there is no effect. When the shedded husk uses this action, it immediately dies.