Brother Karthis

• Fanatical Devotion. When Karthis is reduced to 0 hit points, he makes a DC 10 Con save. On a success, he drops to 1 hit point instead.

• Lair Flames. While fighting in the Ember Sanctum, at the start of each of his turns a random brazier erupts. (Dex save DC 12, 1d6 fire to all within 5 ft.)

Karthis is a 6th-level spellcaster. His spellcasting ability is Wisdom (spell save DC 13, +5 to hit with spell attacks). He requires no material components, calling upon the Hollow Ember.

Cantrips (at will): Thaumaturgy, Sacred Flame, Fire Bolt
1st level (4 slots): Command, Burning Hands
2nd level (3 slots): Hold Person, Spiritual Weapon (manifested as a flaming brand)
3rd level (3 slots): Bestow Curse, Fireball

• Ashen Brand (Melee Spell Attack). +5 to hit, reach 5 ft., one target. Hit: 12 (2d8+3) fire damage.

• Fanatic’s Fire (Recharge 5–6). Karthis exhales a 15-foot cone of blackened flame. Each creature in the area must make a DC 13 Dex save, taking 21 (6d6) fire damage on a fail, or half on a success.

• Command the Flock. Karthis targets one allied cultist within 30 ft. That cultist immediately makes a melee or spell attack as a reaction.

• Ember Step (2/Day). Karthis teleports up to 20 feet to an unoccupied space he can see, leaving behind a puff of ash (creatures within 5 ft. make a DC 13 Con save or are blinded until the start of their next turn).

Karthis can take 2 legendary actions per round, choosing from below:

• Burning Word. Cast Sacred Flame on a creature.

• Fanatical Order. An ally within 30 ft. gains advantage on its next attack.