Necromancers are those that are drawn returning the dead to life. For whatever reason, your character has chosen to pursue this as an obsession, a specialty, forsaking the typical training of wizards, solely focusing on the school of Necromancy and the art of raising the dead.

Necromantic Niche

at 2nd level, due to your usual interest in necromancy, particularly the practice of raising the dead, you have specialized your spellcasting to aid your goals and experience the following changes to Wizard spellcasting:

• You can only learn or copy Necromancy spells, however, these spells can be of any spell list. You may learn cantrips of any spell school from the Wizard spellcasting list.

• ou are capable of using your spell slots to raise the dead. If you have a complete skeleton within range of touch, you may use your bonus action and a spell slot to raise that creature, or potentially creatures from the grave.
  
  The level of the spell slot expended equals the maximum CR of the total raised creature. For example: using a 1st level spell slot, you can raise one CR 1 creature or four CR 1/4 creatures.
  
  Roll Initiative for the risen, which has its own turns. It will obey any verbal commands that you issue to it (no action required by you). If you don't issue any commands to the elemental, it defends itself from Hostile creatures but otherwise takes no Actions. They retain all abilities they had when they were alive. Learned spellcasting is not included, however, innate spellcasting is. If there is no complete skeleton in front of you, you may use an action to use your Drawn to Death ability with a DC determined by your DM depending on the location to reach out to a corpse buried under the earth and raise it. The identity of this creature is chosen by your DM, and the total CR will be equal to the spell slot expended.
  
  Your risen creatures can be sustained until they reach 0 Hit Points or 24 hours since their resurrection, whichever occurs first.

skin and bones

At 6th level, you no longer require full corpses to raise bodies. Instead, you can use simple shards of bone, teeth, or claws, pieces of a wing, etc. collected from the dead.

Slow Rot

At 10th level, your necromantic powers sustain your body. You gain resistance to necrotic damage, your maximum hit point total cannot be lowered by any means. Additionally, your lifespan is slowed; for every 10 years that pass, your body ages only 1 year.

Disrupt life

At 14th level, you've mastered life and death, and can even cull the energy inside living creatures.

As an action, you may force each non-undead creature within 20 ft of you to make a Constitution saving throw against your spell save DC, taking 6d6 damage on a failed save or half as much damage on a successful one. Any creature reduced to zero hit points by failed save is immediately risen under your command.

You may use this ability a number of times equal to your Intelligence modifier per long rest.

Drawn to Death

Additionally, at 2nd level, you can passively sense undead in a 60 ft. radius, as well as the creature type of dead creatures buried beneath the earth. You also learn the Find Familiar spell as a ritual, and can raise a skeletal version of any creature that is not a construct or humanoid with a CR of 0.

Empowered Risen

Additionally, at 6th level, when you raise a creature from the dead, they gain temporary hit points equal to 2 x your Wizard level.