Aunty Hella, The Weird Night Hag

Innate Spellcasting. Hella's innate spellcasting ability is Charisma (spell save DC 16, +6 to hit with spell attacks). She can innately cast the following spells, requiring no material components:

At will: detect magic, magic missile, animate dead,  speak with dead

2/day each: plane shift (self only), ray of enfeeblement, sleep, create undead

Magic Resistance. Hella has advantage on saving throws against spells and other magical effects.

Undead Fortitude. If damage reduces Hella to 0 hit points, it must make a Constitution saving throw with a DC of 5 + the damage taken, unless the damage is radiant or from a critical hit. On a success, the zombie drops to 1 hit point instead.

Claws. (Hag Form Only). Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 13 (2d8 + 4) slashing damage.

Rotting Gaze. (Hag Form Only). Hella targets one creature it can see within 30 feet of it. The target must succeed on a DC 16 Constitution saving throw against this magic or take 14 (3d8) necrotic damage.

Weird Insight. Hella targets one creature it can see within 30 feet of it. The target must contest its Charisma (Deception) check against the nothic’s Wisdom (Insight) check. If the nothic wins, it magically learns one fact or secret about the target. The target automatically wins if it is immune to being charmed.

Change Shape. Hella magically polymorphs into a Small or Medium female humanoid, or back into her true form. Her statistics are the same in each form. Any equipment she is wearing or carrying isn't transformed. She reverts to her true form if she dies.

Etherealness. Hella magically enters the Ethereal Plane from the Material Plane, or vice versa. To do so, the hag must have a heartstone in her possession.

Control Undead. As an action, Hella targets one undead creature she can see within 30 feet of you. The target must make a Wisdom saving throw. On a failed save, the target must obey Hella's commands for the next 24 hours.

Nightmare Haunting (1/Day). While on the Ethereal Plane, Hella magically touches up to 6 sleeping humanoids on the Material Plane. A protection from evil and good spell cast on the target prevents this contact, as does a magic circle. As long as the contact persists, the target has dreadful visions. If these visions last for at least 1 hour, the target gains no benefit from its rest, and its hit point maximum is reduced by one hit die, which is then lost. If the target dies before the spell is broken, and if the target was evil, its soul is trapped in Hella's soul bag. The loss of a hit die and associated reduction to the target's hit point maximum lasts until removed by the greater restoration spell or similar magic, or until Hella dies.