Spoiler Warning: The below article features major spoilers for Final Fantasy 16 and Kingdom Hearts 3.
Donald Duck is no longer the most powerful mage in the history of Final Fantasy thanks to a new big bad taking the title in Final Fantasy 16.
The long awaited RPG is full of humongous, powerful monsters called Eikon that represent Summons from the series' past — Ifrit, Shiva, Phoenix, and so on — and one of these beasties has now wielded the series' most powerful spell.
That Eikon is, final spoiler warning, Bahamut, the legendary dragon king from all the way back in 1987's original Final Fantasy. Bahamut has since appeared in most games in the franchise though, and is considered one of the most powerful magic users.
At a significant moment in Final Fantasy 16 Bahamut wields a spell called Zettaflare, which is an evolution of his previously most powerful spell Megaflare and its variations Gigaflare and Teraflare. This absolutely makes the dragon king the most powerful mage in Final Fantasy lore, with the small caveat that Donald Duck got there first.
In Kingdom Hearts 3, at what is now a heavily mocked moment, Donald Duck wields Zettaflare himself. The move defeats the big bad and knocks Donald unconscious, rightly so, because no character, not even Bahamut, had been capable of wielding Zettaflare previously.
Thanks to Final Fantasy 16, however, Bahamut has regained the most powerful mage title for himself.