Immolith

The spirits of deceased demons occasionally fuse as they fall back into the Abyss that spawned them. The event is unpredictable and unstoppable. The result of this hellish fusion is the horrid demonic entity called an Immolith. As immoliths are formed from the souls of multiple demons, they despise the living more then any other demon and are often more likely to be seen with powerful undead creatures rather then serving other more powerful Tanar'ri.

Appearance
Immoliths look like giant flaming skeletons, often sporting multiple arms. Immoliths use their many claws and their ability to control death fire as their primary weapons in battle. As they are constantly covered in flames, immoliths seem to glide or float but really walk, as this allows them to use their immense size to tower over their enemies.