Bloody Mary, The Red Witch

Wedding Garments. Mary is attuned to all of the following magic items, and wears them at all times: Bride's Brooch (widowed variant), Privacy Veil, Circlet of Gloom, Ring Of Ceremony (wedding variant), Ring Of Ceremony (funeral variant), Boots Of The Slow Dance, Irresistible Eyeshadow, and The Gown Of The Red Wedding.

Lost & Alone. Mary can see 60 feet into the House Of Lost Souls when she is on the Material Plane, and vice versa. In addition, Mary (and any objects she is wearing or carrying) doesn't appear in mirrors and other reflective surfaces unless she wishes to have a reflection.

Incorporeal Movement. Mary can move through other creatures and objects as if they were difficult terrain. She takes 5 (1d10) force damage if she ends her turn inside an object.

Unliving Nature. Mary doesn't require air, drink, food or sleep.

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

Irresistible Magic. Creatures have disadvantage on ability checks made to attempt to counterspell or dispel Mary's spells.

Innate Spellcasting. The Red Witch's spellcasting ability is Intelligence (spell save DC 21, spell attack bonus +13). Mary can innately cast the following spells, requiring no material components:

At will: cause fear, ceremony, hellish rebuke, ice knife, misty step

5/day each: blur, gaseous form, hold person, silence

3/day each: bestow curse, cause fear (3rd-level spell slot), greater invisibility

1/day each: antilife shell, dominate person

Multiattack. Mary uses her Blood Bath ability if it's available. She then makes three attacks: two with her Spectral Knife, and one with her Piercing Gaze.

Spectral Knife. Melee Weapon Attack: +13 to hit, reach 5 ft., one target. Hit: 45 (10d4 + 20) slashing damage plus 45 (10d4 + 20) psychic damage.

Piercing Gaze. Mary targets one creature that she can see within 60 ft. of her that can also see her. That creature must succeed on a DC 21 Wisdom saving throw or become frightened of her for 10 minutes. While frightened in this way, the creature takes 25 (2d4 + 20) psychic damage if they end their turn within 30 ft. of her. The creature can repeat the saving throw at the start of each of their turns, ending the effect on themselves on a success. Once the frightened condition is removed from the creature, they are immune to Mary's Piercing Gaze until the next midnight.

Blood Bath (Recharges after 24 hours). Mary targets a point within 30 ft. of her. Every surface within 20 ft. of that point erupts with blood until everything in the area is caked with it. Every creature within the area when it is created must make a DC 21 Constitution saving throw, taking 100 (30d4 + 25) necrotic damage on a failed save, or half as much on a success. The creature's hit point maximum is also reduced by an amount equal to half the damage taken. Anytime they regain hit points, their hit point maximum increases by the same amount until it has returned to normal.

Hidden Walkways. Mary enters the House Of Lost Souls from the Material Plane, or vice versa.

Incorporeal Movement. Mary automatically escapes from anything that is grappling or restraining her.

The Red Witch can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. She regains spent legendary actions at the start of her turn.

• Mirror Magic. Mary casts misty step.
• Passage. Mary uses her Hidden Walkways ability.
• Bloodlust (Costs 2 actions). Mary reduces the time she needs to wait to use her Blood Bath ability by 4 hours.