Nobody mentioned Gilgamesh yet? the god of war?
i could imagine a strong attack from gilgamesh first and then after he disappears to buff all group members with a very strong attack and critical attack boost to all melee characters.
and his own attack not to be that strong than the elemental attacks such as like ifrits inferno etc. but therefore a buff for all members who summoned him.
It would perfectly fit to FF14 like in FF12 :
for me fenrir doesnt really fit into the role of a "good" its a perfect pet to your side it think like carby for example but with more focus in doint damage than carbuncle. so I would put him more into the "Avatar" list.
