path to lichdom

the lich will grow in power as his path forward is carved into existence 

Grim Harvest

At 2nd level, you gain the ability to reap life energy from creatures you kill with your spells. Once per turn when you kill one or more creatures with a spell of 1st level or higher, you regain hit points equal to twice the spell’s level, or three times its level if the spell belongs to the School of Necromancy. You don’t gain this benefit for killing constructs or undead.

you gain one addition spell to your spells known at 2nd, 5th, 8th, 12th, and 17th level.

 

Undead Thralls

At 6th level, you add the animate dead spell to your spellbook if it is not there already. When you cast animate dead, you can target one additional corpse or pile of bones, creating another zombie or skeleton, as appropriate.

Whenever you create an undead using a necromancy spell, it has additional benefits:

• The creature’s hit point maximum is increased by an amount equal to your wizard level.
• The creature adds your proficiency bonus to its weapon damage rolls.
• At this point your transformation into a lich has begun giving you resistance to Necrotic damage

Undeath

Beginning at 10th level, you have immunity to necrotic damage, and your hit point maximum can’t be reduced. You have spent so much time dealing with undead and the forces that animate them that you have become inured to some of their worst effects.

 you transform more and more gaining resistance to cold damage 

lichdom fulfilled

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.