Angor

Ancient Black Dragon in his life.

Stat Changes
Ancient Black Dragon Stats Monster Manual page 87

Type: Changes from dragon to undead

Damage Resistance: Resistance to necrotic Damage

Damage Immunities: Immunity to poison

Condition Immunities: Can't be charmed, frightened, paralyzed or poisoned. Can't be exhausted.

Magic Resistance: Advantage on saving throws against spells and magical effects.

Becoming a Lich
Angor lived a legendary life. Facing death was not an option. He refused to end his life in such a meaningless way.