Σύρμω

Magic Resistance. The hag has Advantage on saving throws against spells and other magical effects.

Wedding Ring. The hag has a wedding ring. While wearing it, the hag can use its Nightmare Haunting action. When her HP reaches 0 or below, the ring will start healing the hag, after 2 turns. It has to be removed and destroyed, for the hag to die (AC 10, 7 HP).

Aura of Decay. Plants and animals around the hag decay over time, to eventually turn into her undead slaves.

Hag's Mark. The hag can attempt to magically mark a creature. Upon a failed DC 15 Wisdom Saving Throw, the creature carries the Hag's Mark, allowing the hag to see and hear through them.

Multiattack. The hag makes two Claw attacks.

Claw. Melee Attack Roll: +7, reach 5 ft. Hit: 13 (2d8 + 4) Slashing damage.

Nightmare Haunting (1/Day; Requires Wedding Ring). While in her house at Kato Trachanades, the hag casts Dream, using the same spellcasting ability as Spellcasting. Only the hag can serve as the spell’s messenger, and the target must be a creature the hag can see on the Material Plane. The spell fails and is wasted if the target is under the effect of the Protection from Evil and Good spell or within a Magic Circle spell.

If the target takes damage from the Dream spell, the target’s Hit Point maximum decreases by an amount equal to that damage. If the spell kills the target, its soul is trapped in the hag’s wedding ring, and the target can’t be raised from the dead until its soul is released.

Spellcasting. The hag casts one of the following spells, requiring no Material components and using Intelligence as the spellcasting ability (spell save DC 14):

At Will: Detect Magic, Etherealness, Magic Missile (level 4 version), Ray of Sickness (level 2 version)
4/Day Each: Phantasmal Killer, Plane Shift (self only)

3 Legendary actions/long rest.

Dissonant Whispers (modified: a scream that affects everyone around her)