This looks interesting, and seems fitting for a character I wanted to try. However his gimmick is a bit 'unique' even in the typical fantasy world, so before I'd make the sheet for this char I would like your approval for the concept.

Necromancers, more specifically necromancers of the cult hecate (unique to any other necromancer if they exist in this universe) are a group of warlock-necromancers that worship a goddess in the form of a cult. They are all brothers by blood, except for the first necromancer who is the biological father. What makes this concept unique for necromancers is that their 'necromancy' expands more then just death, but aspects of life, biological nature, and undead as well. They can create and destroy life and manipulate biomatter at their whim. While they have an expansive control over power, they are limited by experience. It takes a long time to learn even the more basic aspects of necromancy such as resurrecting zombies or decaying flesh. A fresh necromancer would learn very little of his powers within the typical RP time span, so the character I had in mind wouldn't be overloaded with necromancy abilities, rather just a few basic factors.
Necromancers are mortals, technicly, they can die just as easily as anyone else. However unlike other mortals death doesn't work the same way. Necromancers are essentially inherent masters over the cycles of life and death,so when they die, regardless of the method of destruction, such as being stabbed by a holy sword or completely obliterated to the last atom, they still exist in the mortal world and can regenerate their own bodies or rebuild new ones if they have nothing left of their original bodies. They can also control their bodies at an undead state rather then living. However they are the strongest at a living state, as they cannot use non-necromancy based magic when they are dead, and even then their necromancy becomes very limited. A necromancer can be conventionally defeated in 2 ways. One is to have them exhaust their necrotic energy, typically by killing them numerous times in frequent succession. When this happens, they essentially stop existing until they have regathered enough energy to awaken back in the mortal world, a process that takes a century at the bare minimum. The other, more potentially permanent solution, is some method of powerful sealing or imprisonment, trapping them in a seal of sorts. Ofcourse their is the risk of someone breaking them free.

Necromancers are perpetually stuck at the age they had their first death on, as their first death awakens their abilities, they can be centuries years old yet be stuck as a child.

Now for the character, he would be a sort of 'run away' of the cult, hating his sinister race of necromancers and runs from their pursuit all the while making a life for himself as a mercenary here in the desert wasteland. He has only two abilities, the first being the default, being able to exist after death and regenerate or rebuild a new body if he needs too, the second being able to alter his body portions and mass while in an undead state, such as growing a new, skeletal arm or destroying his own body entirely by his own will. In terms of combat, he sticks with a combat knife and a revolver. He's very young for a necromancer and is fairly inexperienced with his powers, so it wouldn't take too long to send him into a hundred year coma if you kill him a dozen times.