Adyss, the Oracle of Hades

Legendary Resistance (3/Day). If Adyss fails a saving throw, he can choose to succeed instead.

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

Turn Resistance. Adyss has advantage on saving throws against any effect that turns undead.

Learned Defense. Every time Adyss is hit by a Melee or Ranged attack that isn't a spell, his AC increases by 1 when being targeted by that same creature.

Borrowed Time. Adyss gains his power through his connection to Manteo, his home body. He can do any of his spells at will but it will cost him 5 times the spell's level in hit points in order to cast it.

Spellcasting. Adyss' spellcasting ability is Charisma (spell save DC 22, +19 to hit with spell attacks). Adyss has the following spells prepared:
Cantrips: Toll the Dead, Chill Touch
1st level: False Life, Cause Fear
2nd level: Web, Enlarge/Reduce
3rd level: Animate Dead, Beacon of Hope, Lightning Bolt
4th level: Banishment, Counterspell
5th level: Cloudkill, Hold Monster
6th level: Mass Suggestion, Blade Barrier
7th level: Delayed Blast Fireball, Reverse Gravity
8th level: Counterspell, Reality Break
9th level: Time Stop, Prismatic Wall

Scythe. Melee Weapon Attack: +9 to hit, reach 10 ft., one creature. Hit: 18 (2d10 + 7) slashing damage plus 19 (3d12) necrotic damage. Any creature reduced to 0 hit points by this attack dies, with its body and everything it is wearing and carrying, except magic items, exploding into a cloud of ash. The creature can be restored to life only by means of a wish spell.

Invoke Curse (Recharge 6). Targets one creature he can see within 60 feet of him. The target must succeed on a DC 23 Constitution saving throw or be cursed. Until the curse is ended, the target can't regain hit points and has vulnerability to necrotic damage. Greater restoration, remove curse, or similar magic ends the curse on the target.

Breath Weapons (Recharge 5–6). Adyss uses one of the following breath weapons.

Necrotic Breath. Adyss exhales an icy blast in a 20-foot cone. Each creature in that area must make a DC 22 Constitution saving throw, taking 67 (15d8) necrotic damage on a failed save, or half as much damage on a successful one.

Paralyzing Breath. Adyss exhales paralyzing gas in a 20-foot cone. Each creature in that area must succeed on a DC 22 Constitution saving throw or be paralyzed 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.

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

Attack. Adyss makes a Scythe attack.

Move. Adyss moves up to his speed without provoking opportunity attacks.

Spell-casting (Costs 2 Actions). Adyss casts a spell.

Maddening Secrets (Costs 3 Actions). Adyss whispers an arcane secret into the mind of a creature he can see within 30 feet of him. The target must succeed on a DC 22 Wisdom saving throw or expend one of its spell slots of 3rd level or lower and deal 26 (4d12) force damage to each creature within 30 feet of it. A creature that fails the saving throw but can't expend a spell slot is instead stunned until the end of its next turn.