Corpomancy Prodigy

Beginning when you chose this tradition at 2d level you've learned all the basics of bodily functions and medicine. You gain proficiency in medicine, or if you're already proficient, expertise. Additionally whenever you gain a wizard level, you can replace one of the wizard spells you add to your spellbook with a spell from the extended spell list provided.

These spells count as wizard spells to you, but cannot be chosen for your level 18 Spell Master feature or your level 20 Signature Spell feature if they were not on the Wizard Spell List previously. The spell must be of a level for which you have spell slots. If the spell is already on the Wizard Spell List the cost of scribing it into your spellbook is halved.

Necrotic Transference

At 2nd level, you gain the ability to harvest and transfer 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 or a creature within 30 feet of you that you can see regain hit points equal to twice the spell 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.

At 6th level you can use this feature once per short rest to instead heal yourself and up to three creatures within reach.

Spell Rot

As you reach 6th level, you've learned to twist the energies of your damaging spells to make them affect the body and its life energy directly. When you use a spell slot and the spell deals damage you can chose to change the damage type to necrotic.

Additionally, when you use a spell attack to cast a cantrip, you can spend a spell slot to deal an additional 2d8 necrotic damage for a level 1 slot, and an additional 1d8 for each level above the first up to a limit of 5.

Of Life and Death

By 10th level, you have gained a deeper understanding of life and death and everything in between, giving you unusual control over your spirit even in an unconscious state. When you are reduced to 0 hit points, your spirit and body are separated. You cannot cast spells or take the attack action, but you also do not need to make any death saving throws.

While out of your body you can float around freely at a flight speed of 60ft and phase through physical objects such as walls. Allies will be able to see your ghostly form and you can still speak to them.

This state can last up to 1 minute and you must return to your body or fail a death saving throw for each turn spent out of your body thereafter. Once you return to your body, you must make death saving throws like normal. If you are healed while your spirit and body are separated, you will return to consciousness and your spirit will instantly be drawn back into your body. Once you've used this feature you can't use it again until you've finished a short or long rest.

Reap Undead

Starting at 14th level, your knowledge of the undead and the body allow you to bypass the necrotic resistance and immunities of undead creatures.

When you attack an undead creature with a spell dealing necrotic damage, it ignores eventual resistances, instead dealing full damage, and partially ignores immunity, dealing half damage as if the creature had only resistance. When you kill an undead creature with a CR equal to your
level or less this way, they cannot rise again
and are put to rest for good.