Bahamut's appeared as a boss, ally, summon, and more in many Final Fantasy games, including his significant role in Final Fantasy XIV: A Realm Reborn
While this is a serious restriction on the mechanic (itd be much more powerful if you got a benefit every time you played a spell), this restriction allows cards to be more aggressively costed
We know which rares and mythics have a Borderless version and a Textured version
The sets are cheap, and they can make a lot of them
While you are limited to only drawing one card each turn, pairing Dina with token producers and free instant speed sacrifice outlets like Ashnods Altar makes it trivial to draw tons of cards
( edit: this doesnt work either, as the Crucible does in fact exile the targeted card youll have to find better ways to make a hundred copies of Wall of Tombstones