You are better than those who try and become a regular lich, because you'll take your time and are more patient.

Bonus Cantrip

Beginning when you select this school at 2nd level, you gain the Chill Touch cantrip. This doesn't count against the cantrips you already have known.

Healing Through Suffering

Beginning at 2nd level, you can heal from the suffering you inflict upon others. When you cast a spell of 1st level or higher you heal 1d6 + the spell's level hit points.

Extra Spells

You gain extra spells at 2nd level, 5th level, 8th level, 11th level, 14th level, and 17th level.

Harrowing Cantrip

Starting at 6th level, your damaging cantrips affect even creatures that avoid the brunt of the effect. When a creature is subjected to one of your cantrip, the creature takes an additional 1d6 necrotic damage. There is no saving throw for this damage.

Empowered Spellcasting

Beginning at 10th level, you can add your Intelligence modifier of d8's to your spells if you have advantage on the attack roll or the target has disadvantage on the saving throw.

Lichdom

Starting at 14th level, you have made a phylactery and are now immortal If you still have a phylactery, you gain a new body in 1d10 days, regaining all of your hit points. Your new body appears within 5 feet of the phylactery.

You also gain a lich's paralyzing touch feature. You make a melee spell attack against a creature within 5 feet of you, dealing 3d6 cold damage and forcing the target to make a Constitution saving throw or be paralyzed for 1 minute. The target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. You can do this twice per Long Rest.