Auntie Sherri Q

Innate Spellcasting. Sherri Q's innate spellcasting ability is Charisma (spell save DC 17, +9 to hit with spell attacks). She can innately cast the following spells, requiring no material components:

At will: detect magic, magic missile

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

1/day each: geas, cloudkill, blindness/deafness (at level 3), nystul's magic aura

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

Ravenous Furnace. At the start of her turn Sherri Q can choose to consume a charge from the Jewel of three prayers, and regain a single use of one of her spells or limited abilities (i.e. Nightmare haunting, Consume Spell.). If she does not do so, all creatures effected by her legendary actions may immediately roll a saving throw to end the effect of the action they are under.

Otherwise, If Sherri Q is within 5 ft. of a runechild that has at least one charged rune, she can make a single unarmed melee attack. On a hit, it deals no damage, but the runechild loses 1 charged rune, and creatures effected by Sherri Q's legendary actions do not get to roll a saving throw.

The Jewel of Three Prayers (Awakened). Depending on the story, Sherri Q might have access to the Jewel of Three Prayers (awakened).

Multiattack. Sherri Q makes two stone knife attacks.

Stone Knife (Hag Form Only). Melee or Ranged Weapon Attack: +8 to hit, reach 5 ft. or range 20/60 ft., one target. Hit: 14 (4d4 + 4) slashing damage. The Stone Knife magically returns to Sherri Q's hand after attacking.

Change Shape. Sherri Q 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. Sherri Q magically enters the Ethereal Plane from the Material Plane, or vice versa. To do so, the hag must have a heartstone in her possession.

Nightmare Haunting (1/Day). While on the Ethereal Plane, Sherri Q magically touches a sleeping humanoid 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 5 (1d10). If this effect reduces the target's hit point maximum to 0, the target dies, and if the target was evil, its soul is trapped in Sherri Q's soul bag. The reduction to the target's hit point maximum lasts until removed by the greater restoration spell or similar magic.

Consume Spell (3/day). After making a saving throw against a spell, success or fail, Sherri Q can choose to consume it. The spell has no effect and Sherri Q can either regain Legendary actions equal to a third of the level of spell consumed (rounded up), or, on her next turn, cast the spell herself, using the original caster's spell save DC.

Devour Sight. Sherri Q makes one stone knife attack. If the target is a creature, it must succeed on a DC 17 Constitution saving throw or become blinded for 1 minute. The target Can repeat the saving throw at the end of each of its turns. While a creature is under the effects of Devour Sight, Sherri Q gains Blindsight to a range of 60 feet and cannot use this legendary action again.

Devour Mind (Costs 2 Actions). Sherri Q makes one stone knife attack. This attack deals psychic damage instead of slashing. If the target is a creature, it must succeed on a DC 17 intelligence saving throw. On a fail, for the next minute, it rolls a d6 and subtracts the number rolled from all its attack rolls, ability checks, and saving throws. The target can repeat the saving throw at the end of each of its turns. While a creature is under the effects of Devour Mind, Sherri Q gains the Inverse of this effect. She rolls a d6 and adds the number rolled to all her attack rolls, ability checks, and saving throws, and cannot use this legendary action again.

Devour Heart (Costs 3 Actions). Sherri Q makes one stone knife attack. This attack deals necrotic damage instead of slashing. If the target is a creature, it must succeed on a DC 17 wisdom saving throw or become frightened for 1 minute. While frightened in this way, the target must take the Dash action and move away from her by the safest available route on each of its turns, unless there is nowhere to move or it is 60 feet or further from Sherri Q. Also, at the end of each of its turns, the effected target takes 16 (3d10) necrotic damage, and can repeat the saving throw. When a creature takes this damage, Sherri Q gains an equal amount of hit points. As long as a creature is under the effect of Devour heart, Sherri Q cannot use this legendary action again.