Charron, the Horseman of Death

Aura of Dread. Charron emits an aura that dampens one's ability to overcome magical effects. Anyone with 10 feet of Charron has disadvantage on saving throws.

Undead Health. If Charron is hit with Necrotic damage, he instead takes the half the damage as healing.

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

Legendary Resistance (3/day). If Charron fails a saving throw, he can choose to succeed.

Spellcasting. Charron is a 5th-level spellcaster. Its spellcasting ability is Wisdom (spell save DC 17, +9 to hit with spell attacks). Charron has following spells wizard prepared:
Cantrips (at will): Control Flame, Infestation, Light, Mage Hand, Toll the Dead
1st level (4 slots): Ray of Sickness, Unseen Servant, Witch Bolt
2nd level (3 slots): Blindness/Deafness, Ray of Enfeeblement, Misty Step
3rd level (3 slots): Counterspell, Spirit Shroud
4th level (2 slots): Blight, Dimension Door, Confusion
5th level (1 slot):  Dominate Person, Immolation

Face of Death. Charron can remove his hood and expose his full face. Anyone within 60 feet that can see his face must make a DC 15 Wisdom saving throw or become frightened until the end of his next turn. If a creature succeeds on the saving throw, it is immune to this ability in the future. He will usually do this just as combat starts.

Multiattack. Charron may make 2 melee attacks or one Touch of Death attack, if he does not cast a spell.

Skeletal Swipe. Melee Weapon Attack: +5 to hit, reach 10 ft., 1 target. Hit: 9 (2d6 + 5) slashing damage.

Skeletal Stab. Melee Weapon Attack: +5 to hit, reach 10 ft., 1 target. Hit: 9 (2d6 + 5) piercing damage. If this attack hits, the targeted creature must make a DC 18 Strength saving throw or be pull within 5 feet of Charron.

Touch of Death (Recharge 6). Charron reaches out and touches one creature within 10 feet. The creature must make a DC 18 Constitution saving throw. If the creature fails the saving throw, they take 30 (8d6) necrotic damage, or half if they succeed. 

Cloak of the Warden (1 charge). If Charron is targeted by a spell of 3rd level or lower that only targets him, he may use a reaction to reflect it. If he does so, the spell has no effect on him and instead targets the caster, using the spell slot, spell save DC, attack bonus, and the spellcasting ability of the caster. This can only be done once.

Charron 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. Charron regains spent legendary at the start of its turn.

Unimpeded Movement (Costs 1 Action). Charron may use a legendary action to move 30 feet without provoking attack of opportunities.

Murderous Relief (Costs 2 Actions). If Charron has minions around him, he may kill one and steal their life force, healing himself for 30 hit points.