Crimson Executioner

Legendary Resistance (3/day). If the crimson executioner fails a saving throw, it can choose to succeed instead.

Incredible Strength. The executioner holds his greataxe with one hand.

Lantern Spirits. If the executioner has a soul trapped in a lantern at the start of his turn, he regenerates 11 (2d10) hit points.

Innate Spellcasting. The executioner's spellcasting ability is Constitution (spell save DC 17, +9 to hit with spell attacks). It can innately cast the following spells, requiring no material components:

At will: detect magic, feather fall, continual flame

2/Day: dispel magic

1/Day:  earthquake

Multiattack. The executioner makes two attacks, only one of which can be a soul steal attack.

Greataxe. Melee Weapon Attack: +11 to hit, reach 5 ft., one target. Hit: 12 (1d12 + 6) slashing damage plus 3 (1d6) necrotic damage.

Unarmed Strike. Melee Weapon Attack: +11 to hit, reach 5 ft., one target. Hit: 10 (1d8 + 6) bludgeoning damage. The target must succeed on a DC 18 Strength saving throw or be knocked prone.

Soul Steal. The executioner targets one creature it can see within 60 feet of it. The target must succeed on a DC 17 Constitution saving throw or take 7 (2d6) necrotic damage on a failed save, and half as much on a successful save. On a failed save, the target is also stunned until the end of its next turn, and at the start of every subsequent turn it has it must make the saving throw again until it has made a total of three successful or three failed saving throws, whichever comes first (the initial failed save counts as 1 failure). On three successes, there is no further effect. On three failures, the target's soul is trapped inside a magical lantern (AC 19, 25 hp) that hangs from the executioner until the lantern is destroyed. The lantern is immune to any spells or magical effects that do not originate from the executioner, and is resistant to damage from non-magical weapons. If trapped this way, the creature's body becomes a lifeless corpse, it is also under the effect of the gentle repose spell for 3 days.

Every round a creature's soul remains inside the lantern, the creature's hit point maximum is reduced by 11 (2d10) points. If a creature's maximum hit points is reduced to 0 in this way, the creature's soul is permanently trapped inside the lantern until either: the executioner dies or, the soul is brought back by casting a wish spell, the resurrection spell, or the true resurrection spell on the creature's body. If the creature's soul is returned to its body before its maximum hit points becomes 0 this way, the reduction lasts until the creature finishes a long rest, otherwise a creature's maximum hit points are restored to normal upon returning to the body.

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

Move. The executioner moves up to its speed without provoking opportunity attacks.

Unarmed Strike. The executioner makes one unarmed strike.

Cast a spell (Costs 2 actions). The executioner can cast one spell that it knows.