True Zombification

The might of the death magic lore, of which Beleg the Necromancer with many faces is a master, flows through your veins and gives you nigh over natural powers, that you can use to your advantage.

You touch a creature that has been dead for no longer than 1 hour to revive it as a zombie. This spell doesn‘t close wounds or replace damaged or missing organs and limbs. The creature fights with its original stat block. If the creature was undead, it is restored to its original form. If the creature wasn‘t undead, it‘s revived form gets the category Undead.   Additionally, the revived creature gains immunity against poison damage and the poisoned condition. Since its soul already left its body, the creature gains immunity against necrotic damage as well. Last but not least your revived gains the feature Undead Fortitude. If damage reduces the revived to 0 hit points, it must make a Constitution saving throw with a DC of 5 + the damage taken, unless the damage is radiant or from a critical hit. On a success, the revived drops to 1 hit point instead. The zombification lasts for 8 hours  or until the zombie is reduced to 0 hit points. Both ways, the spell leaves a corpse behind, immune against all types of necrotic magic.