Defluo's first and only Exarch before he vanished from the world of Galara mysteriously. Created by placing one of the discarded eggs of an early dragon experiment performed by Ator in the palce of the heart within the corpse of Agrilnost, and then infused with divine energy by the god of dragons. It took the corpse thousands of years to truly return to full function, at which time without a master it claimed the egg created in a parallel experiment, and moved to roam the world at it's own whim.
Tiamat's only difference from the one presented in the cannon books is that the black dragon head is replaced by a Grey Dragon head. This is purely a fluff difference.