[Wizzil]

DrPraetorious provides a rather nice discription, though may i add for game purposes they can be like berserkers fighting in a whirlwind like motion.

I'll get on with the mythological creatures:

Djinn: the basic type of otherworldy creature in middle eastern mythology, they can be taken in any direction and have many other "castes", though the basic djinn is usually considered as some sort of air spirit or tied to the air element generally.

Marid: Coastal Djinn, huge in size, usually cruel creatures that torture their prey by asking almost impossible riddles before eating them whole.

Efreet: Generally small djinn, their size may reach that of a human, very fiery in nature and destructive.

Selbouh: not related to the djinn, a sentient froglike creature with big eyes, usually they stalk their pray in rivers, skewering them with spears and dragging them into the bottom of the river to consume them.

Ghul: formerly they were human, but madness has destroyed their minds, they usually dig out graves and eat the corpses within them.

i haven't played much yet of the game to give the units roles, so i'll leave it to the author, seeing how djinns generally vary they can fit in pretty much everything (like for instance Ifreets as skirmisher type of units, firing flaming arrows and fighting with swords enchanted with fire), maybe have them conjured as some sort of national magic that depends on the school of magic you take.