Bellum, Exarch of War

Exarch's Sight. Magical darkness doesn't impede the Exarch's vision.

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

Spellcasting. Bellum is a 20th-level spellcaster. His spellcasting ability is Intelligence (spell save DC 19, +15 to hit with spell attacks). He has the following wizard spells prepared:

Cantrips (at will): fire bolt, light, prestidigitation, ray of frost, shocking grasp

1st level (4 slots): detect magic, magic missile, shield, thunderwave, unseen servant

2nd level (3 slots): blur, enlarge/reduce, flaming sphere, scorching ray

3rd level (3 slots): counterspell, fireball, hold person, lightning bolt, slow

4th level (3 slots): confusion, dimension door, fabricate

5th level (2 slots): conjure elemental, polymorph, wall of fire, wall of force

Displacement and Avoidance.  Bellum projects an Illusion that makes him appear to be standing in a place near his actual location, causing any creature to have disadvantage on Attack rolls against him. If Bellum takes damage, the property ceases to function until the start of his next turn. This property is suppressed while Bellum is Incapacitated, Restrained, or otherwise unable to move. If Bellum is subject a Dexterity saving throw and succeeds the saving throw, he takes no damage. If Bellum fails then he only takes half of the damage. 

The Names Have Power. Bellum attends by many names, but only one true name. If any creature pronounces his true name, Bellum immediately knows their location within 5 miles of where they are and what plane they are on.

Claws of the Jabberwok Slayer. Shards of a Vorpal Sword once broken against the Exarch replace its claws. A successful DC 12 Intelligence (Arcana) or Wisdom (Perception) check identifies them as such. When the Exarch rolls a 20 on an attack roll with a claw, the target is decapitated. (At your option, the attack can instead deal an extra 6d8 slashing damage.) A target is immune to this effect if it is immune to slashing damage, has legendary actions, doesn’t have or need a head, or if you decide that the target is too large for its head to be cut off by the Exarch’s claws. If removed, the shards lose their magical powers.

Anathemic Endurance. The exarch doubles it constitution modifier when calculating hit points. In addition, the exarch has resistance to all damage except force, radiant, and psychic damage. 

Mantle of the Fury/Abandon Reason. Bellum can choose to begin radiating an aura of pure fury and hate even though he is completely complacent. Every creature in this 60 ft aura of red seeping energy must make a DC 25 Wisdom saving throw at the beginning of their turn or be charmed*(filled with rage). While this is happening they must take their full action, bonus action, and movement to get within melee distance of Bellum and if possible melee attack. They continue to do this until they either kill Bellum, drop to 0 hit points, or break the charm. This save can be remade at the beginning of the target's turn. If the target succeeds they are immune to this effect for 24 hours.

Marked for the Cull/of Those Marked to fall. While a creature marked for the cull the target ignores all resistances against Bellum and has advantage on all attacks and saving throws. A long Ethereal chain runs from the target to Bellum this can be removed via a greater restoration or a remove curse. This effect ends after the cull begins, the curse is removed, or the target is incapacitated.

Legendary Resistance (4/Day). If Bellum fails a saving throw, he can choose to succeed instead.

Magic Resistance. Bellum has advantage on saving throws against spells and other magical effects.

Magic Weapons. Bellum’s weapon attacks are magical.

Immutable Form. The creature is immune to any spell or effect that would alter its form.

Undetectable. Bellum can’t be targeted by divination magic, perceived through magical scrying sensors.

Multiattack. The Exarch makes four attacks: three attacks with its claws and one with it's eyes.

The Cull(Recharge 19-20{must have at least 2 people marked}). Bellum forces all targets marked for the cull to make death saving throws until one target dies. Make the death saving throws in the initiative order, and once a target dies all other targets take 20d6 force damage and stop rolling death saving throws. The Cull ends after this effect. 

Claws. Melee Weapon Attack: +18 to hit, reach 10 ft., one target. Hit: 30 (4d8 + 12) slashing damage. On a critical hit refer to Claws of the Jabberwok Slayer. 

Reaping Arms (Recharge 5–6). The Exarch makes a separate claw attack against each creature within 15 feet of it. Each creature that is hit must also succeed on a DC 17 Dexterity saving throw or be knocked prone.

 Teleport (recharge 3-6). Bellum magically teleports, along with any equipment he is wearing and carrying, up to 120 feet to an unoccupied space he can see.

Eyes of War. Ranged Weapon Attack: +18 to hit, 60 ft., one target. Hit: 24 (3d8 + 12) psychic damage and the target must succeed on one of the following effects, you can decide via rolling (1d6) and choosing. Note: if the target is wearing a magical mask, then they either have advantage on all of the following saving throws, and if they have a Mask of the Flow they are immune to any and all of these effects. If a target is hit by an eye attack and fail the DC 25 saving throw they must make an additional DC 20 Charisma Saving throw or gain Marked for the Culling.

- (1) Mind over Muscle. DC 25 Constitution saving throw or be stunned until the end of the target’s next turn. 

- (2) Overwhelming Odds. DC 25 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to this effect for the next 24 hours.

- (3) Weight of War. DC 25 Strength saving throw as a massive invisible weight is placed upon the target. Upon failing they are crushed taking 20 (4d10) Force damage and are restrained. upon success they are unaffected and they take no damage.

- (4) Fatigue of War. DC 25 Constitution saving throw or the target takes a point of exhaustion.

- (5) Winds of War. DC 25 Dexterity saving throw or the target takes 35(7d10) piercing damage and is thrown back 30 feet while being pushed prone. Success will only see the target knocked back 10 feet while taking half damage.

- (6) Call of War. DC 25 Charisma saving throw, if the target fails they are considered mind charmed and mind controlled. taking damage can force them to remake the save as well as the beginning of their turn.

Geryon 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. Geryon regains spent legendary actions at the start of his turn.

Teleport(Costs 1 Action). Bellum uses his Teleport action.

Claw(Costs 2 Actions). Bellum uses his claw attack

Eye(Costs 3 Actions). Bellum uses his eye attack

The Cull(Costs 3 Actions). Bellum begins the Cull.

 Casting a Cantrip(Costs 2 Actions).

Casting a Spell(Costs 3 Actions).