Devotion's Call (1/Day).

The medusa can cast the Resurrection spell, requiring no material components and using Wisdom as the spellcasting ability.

Legendary Resistance (4/Day).

If the medusa fails a saving throw, it can choose to succeed instead.

Actions

Multiattack.

The medusa makes one Constrict attack, one Final Blade attack, and one Snake Hair attack. Alternatively, it makes two Wrathful Strike attacks.

Constrict.

Melee Weapon Attack: +12 to hit, reach 10 ft., one target. Hit: 16 (3d6 + 6) bludgeoning damage, and if the target is a Medium or smaller creature, it has the grappled condition (escape DC 20). Until this grapple ends, the target has the restrained condition, and the medusa can't constrict another creature.

Final Blade.

Melee Weapon Attack: +12 to hit, reach 5 ft., one target. Hit: 13 (2d6 + 6) slashing damage plus 21 (6d6) force damage. If the target has at least one head and the medusa rolled a 20 on the attack roll, the target is decapitated and dies if it fails a DC 20 Constitution saving throw and can't survive without that head. A target is immune to this effect if it takes none of the damage, has legendary actions, or is Huge or larger. Such a creature takes an extra 28 (8d6) force damage from the hit.

Snake Hair.

Melee Weapon Attack: +12 to hit, reach 5 ft., one target. Hit: 11 (1d10 + 6) piercing damage plus 5 (1d10) poison damage.

Wrathful Strike.

Ranged Spell Attack: +12 to hit, range 120 ft., one creature. Hit: 22 (3d10 + 6) radiant damage, and the target has the blinded condition until the end of its next turn.

Spellcasting.

The medusa casts one of the following spells, requiring no material components and using Wisdom as the spellcasting ability (spell save DC 20):

At will: Light, Spare the Dying, Thaumaturgy
2/day: Mass Cure Wounds (cast at 8th level)
1/day each: Blade Barrier, Divination, Greater Restoration

Bonus Actions

Petrifying Gaze (Recharge 4–6).

The medusa unleashes petrifying magic from its eyes in a 30-foot cone. Each creature in that area must make a DC 18 Constitution saving throw if it doesn't have the blinded condition. If the saving throw fails by 5 or more, the creature has the petrified condition. Otherwise, on a failed save, the creature takes 10 (3d6) force damage, begins to turn to stone, and has the restrained condition. The restrained creature must repeat the saving throw at the end of its next turn. On a failed save, it has the petrified condition, and on a successful save, the effect ends on it. The petrification lasts until the creature is freed by the Greater Restoration spell or other magic.

A creature can use its reaction, if available, to shut its eyes to avoid the saving throw. If the creature does so, it has the blinded condition until the end of its next turn.

Legendary Actions

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

Move. The medusa moves up to its speed without provoking opportunity attacks.
Wrathful Blast (Costs 2 Actions). The medusa makes one Wrathful Strike attack.
Final Slash (Costs 3 Actions). The medusa makes one Final Blade attack with advantage.

Lair Actions

On initiative count 20 (losing initiative ties), the medusa can take one of the following lair actions; the medusa can't take the same lair action two rounds in a row:

Petrifying Wave. Up to three creatures the medusa can see within the lair are partially turned to stone. Each target must make a DC 15 Constitution saving throw. On a failed save, a target's speed is reduced to 0 and can't increase. On a successful save, its speed is halved. The target's speed returns to normal on initiative count 20 on the following round.
Sudden Stonework. The medusa creates a wall of stone on a solid surface it can see within the lair. The wall can be up to 60 feet long, 20 feet high, and 1 foot thick. Each 5-foot section of the wall has an AC of 17; 30 hit points; vulnerability to thunder damage; and immunity to poison, psychic, and slashing damage. A creature in the wall's space when the wall appears is pushed to the nearest unoccupied space on one side of the wall and must make a DC 15 Dexterity saving throw. On a failed save, the medusa chooses the side. On a successful save, the creature chooses the side. The wall disappears when the medusa uses this lair action again or when the medusa dies.
Undulating Surface. Solid surfaces within the lair ripple like a snake's coils. Up to three creatures the medusa can see within the lair can move up to 30 feet along solid surfaces without provoking opportunity attacks. If a creature moves along a surface such as a ceiling with no way to remain there (for example, sufficient handholds), it falls at the end of this movement.

Regional Effects

The region containing a medusa's lair is altered by the medusa's presence, creating one or more of the following effects:

Faces in Stone. Stone within 3 miles of the lair takes on subtle shapes that suggest people, animals, and other creatures when viewed from the corner of the eye or through dim light or fog.
Gathered Knowledge. Within the lair, creatures have advantage on ability checks made to discover or recall information relevant to the medusa's divine purpose.

If the medusa dies, these effects fade over the course of 1d10 days.

Hierophant Medusa