Multiattack

The mavka makes two Enervating Slam attacks or three Necrotic Bolt attacks. If she is riding a nightmare, the nightmare can then make one Hooves attack. If both Enervating Slam attacks hit one creature, the mavka regains hp equal to the total necrotic damage dealt by both attacks.

Enervating Slam

Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 23 (4d8 + 5) bludgeoning damage plus 16 (3d10) necrotic damage.

Necrotic Bolt

Ranged Spell Attack: +8 to hit, range 60 ft., one target. Hit: 26 (4d10 + 4) necrotic damage.

Flame Burst (Recharge 5-6)

While riding a nightmare, the mavka channels her power into her mount, causing its fiery light to burn those nearby. Each creature within 20 feet of the mavka must make a DC 16 Dexterity saving throw, taking 54 (12d8) fire damage on a failed save, or half as much damage on a successful one.

Spellcasting

The mavka casts one of the following spells, requiring no material components and using Charisma as the spellcasting ability (spell save DC 16): At will: create or destroy water, dancing lights 3/day each: darkness, hold person, silence 1/day each: bestow curse, dispel magic