Burning Effigy

Illumination. The burning effigy sheds either dim light in a 15-foot radius, or bright light in a 15-foot radius and dim light for an additional 15 feet. It can switch between the options as an action.

Magic Resistance. The burning effigy has advantage on saving throws against spells and other magical effects.

Flaming Aura. The burning effigy gives off heat in a radius of 20 feet. When a creature enters that area or begins its turn there, it suffers 10 (3d6) fire damage.

Turn Resistance. The burning effigy has advantage on saving throws against any effect that turns undead.

Spellcasting. The burning effigy is a 9th-level spellcaster. Its spellcasting ability is Charisma (spell save DC 14, +7 to hit with spell attacks). It requires no somatic or material components to cast its spells. The burning effigy knows the following warlock spells:

1st-5th level (2 5th-level slots): burning hands, hellish rebuke, fireball, wall of fire

Multiattack.  The burning effigy uses Necrotic Fire Ray twice.

Necrotic Fire Ray. Ranged Spell Attack: +7 to hit, range 120 ft., one target. Hit: 10 (3d6) fire damage and 10 (3d6) necrotic damage. The target must succeed on a DC 14 Constitution saving throw or its hit point maximum is reduced by an amount equal to the damage taken. This reduction lasts until the target finishes a long rest. The target dies if this effect reduces its hit point maximum to 0. 

Maelstrom (Recharge 6). The burning effigy creates a storm of fire, ash and smoke in a radius of 30 feet around itself. Creatures within the maelstrom must make a DC 14 Dexterity saving throw, suffering 35 (10d6) fire damage on a failed save or half as much damage on a successful one. This area is heavily obscured until the start of the burning effigy's next turn.

Hellish Rebuke. The burning effigy casts the hellish rebuke spell at 1st level without using a spell slot.