Zelda knock-off villain

Bulan is ancient, probably older than the universe; she, along with the rest of her people, was imprisoned by another ancient race for learning too much about the old races, the old technology, and older magic.

Now she's back, and she's pissed off. She's taken the guise of a newly-sentient AI and is using the people of the only habitable world left in the universe to perform an ancient spell to send herself back to her original timeline to punish the other race.

She's nuts, not just from a human perspective but in the grand scheme of things; her ritual won't do anything except blow up the planet.