Special Equipment. Sasha wears a magic gown that grants her a +2 bonus to AC and a +1 bonus to saving throws (included above).
Spellcasting. Sasha casts one of the following spells, using Intelligence as the spellcasting ability (spell save DC 18):
Cantrips (at will): mage hand, toll the dead, [spell]chill touch/spell]
1st level (4 slots): cure wounds, cause fear, shield, silent image
2nd level (3 slots): phantasmal force, ray of enfeeblement, invisibility, mirror image
3rd level (3 slots): fear, counterspell, major image, summon shadowspawn
4th level (3 slots): summon aberration, phantasmal killer
Multiattack. Sasha makes three Necrotic Strike attacks or two claw attacks
Necrotic Strike. Melee or Ranged Spell Attack: +10 to hit, reach 5 ft. or range 120 ft., one target. Hit: 32 (5d10 + 5) necrotic damage.
Claw Melee Weapon Attack: +1 to hit, reach 5ft, one target, Hit (2d6 + 4) slashing damage.
Sing (5/day) Sasha releases a debilitating beautiful song. All who can hear it within 120ft must succeed a constitution saving throw of DC20 or be charmed. At the end of each of its turn, the target can make another con save. On a Success, the condition ends and they become immune to the her song for the next 24 hours.
As a bonus action the siren can move the charmed targets 10ft closer to them.
Horrifying Visage. Each non-undead creature within 60 feet of the banshee that can see her must succeed on a DC 18 Wisdom saving throw or be frightened for 1 minute. A frightened target can repeat the saving throw at the end of each of its turns, with disadvantage if the banshee is within line of sight, ending the effect on itself on a success. If a target’s saving throw is successful or the effect ends for it, the target is immune to the banshee’s Horrifying Visage for the next 24 hours.
Wail. Sasha releases a mournful wail. This wail has no effect on constructs and undead. All other creatures within 30 feet of her that can hear her must make a DC 18 Constitution saving throw. On a failure, a creature drops to 0 hit points. On a success, a creature takes 10 (3d6) psychic damage