I got the zombii concept from a number of places, namely two being Wikipedia and the Holy Lands Devil Hunter's Manual. (Sorry no links)

as for the burning material, the demonic spirit that is manifesting into the dead body must be an extremely strong fire elemental type, which would burn the body in the manifestation. Sorry about the idea, especcially since my ideas clash with San's. Nuff said. just drop this idea. Ill try something else.

rolemaster

I did some research. Santharia is wrong ...
Zombiis are dead bodies (of any race) that have been possessed by a demonic (or otherwise evil) spirit and controlled by that spirit. A necromancer can summon a spirit to control the body and possibly do his bidding. A Zombii is not mindless, but rather a manifestation of a demon's being.

I need a little help here...I am not much for magic...what type of character would manifest a demon into a zombii like being?

Ok, so I changed everything you indicated...Now what?

Basic Overview: Wherever a dead body is, an Ash Zombii can manifest. Some flame-oriented demons can enter the form of a dead body and control it. Because they are flame-oriented, the body ignites when it rises up out of the ground.
Appearance: An Ash Zombii looks like a black, charred skeleton; as any remaining skin, clothing, etc. remaining was burned off during the manifestation. An Ash Zombii is ignited with an evil flame covering it's entire body.
Special Abilities: *An Ash Zombii can quickly move upwards through any substance thicker than light soil, thus coming out of a grave, etc. *An Ash Zombii can see any invisible character, regardless of the nature of the invisibility. *An Ash Zombii can summon a non-magical fireball from the flame around it's body and throw it at enemies.
Territory: Ash Zombiis can exist nearly anywhere; virtually wherever there is a dead body.
Habitat/Behavior: Ash Zombiis are simply demonic beings controlling the body, so the behavior is based on the controller. For habitat, see Territory (above).
Diet: Ash Zombiis have no need for food and sleep, as they are in an undead state, neither living nor dead.
Mating: Ash Zombiis cannot mate.
Myth/Lore/Origin: Myth has it that Ash Zombiis can be slain easily with mithril weapons, but this has not been confirmed. Ash Zombiis can be created in one of two ways: a demon can manifest itself into the body and take control or a necromancer (or similar) summons a demon to control it. This summon places the being inside the body without the consent of the summoned spirit, thus making an angry spirit sometimes attack the summoner.
Weakness: Ash Zombiis take double the normal damage from any holy weapons, and from all silver weapons. Simple silver-coated weapons deal only a little bit more.
Immunity: Ash Zombiis are immune to all fire, poison, and venom.