Lichdom

Through the usage of extremely powerful necromantic magic or through a pact with a godlike evil entity related to undeath, you have effectively become a Lich and gained all the characteristics of such:

• Undeath: You are considered an undead creature, you do not need to sleep in order to rest, you do not need to eat to sustain yourself, you do not grow any older, you are immune to nonmagical diseases, you do not need to breathe and you cannot be healed through normal means nor conventional healing spells;
• Damage Resistance: cold, lightning, necrotic;
• Damage Immunities: poison; bludgeoning, piercing, and slashing from nonmagical attacks;
• Condition Immunities: charmed, exhaustion, frightened, paralyzed, poisoned;
• Truesight: 120 ft.;
• Legendary Resistance (3/Day): If the lich fails a saving throw, it can choose to succeed instead;
• Rejuvenation: If it has a phylactery, a destroyed lich gains a new body in 1d10 days, regaining all its hit points and becoming active again. The new body appears within 5 feet of the phylactery;
• Turn Resistance: The lich has advantage on saving throws against any effect that turns undead;
• Accomplished Caster: The lich gains knowledge and can once a day cast 1 additional spell of your choice of each level from the Wizard's spell list;