That ultimate is broken, but I guess no more so than Tamiyo's. If there wasn't precedent, I'd say it should exile the spell upon resolution, like flashback.

That is an interesting point... the ultimate is pretty good with a single Lightning Bolt isn't it?

I first thought of a fast mana spell like Pyretic Ritual, which gives infinite mana. If your subsequent Fireball doesn't resolve, you could always try Grapeshot with infinite storm count.

That makes sense... but looking at how powerful that ultimate is with a combo is probably a trap, if we're trying to figure out if it's broken or not. The ultimate + Boomerang + 6 Islands should be all the combo you need.

It should probably exile instants/sorceries after you cast them this way; like most other "from graveyard" things. That way most of the worst abuses are avoided; while still staying rather good when combined with, well, itself really.

Though combing it with the spellbombs (or a black lotus) is still going to be massively abusable; I don't think that's a thing worth worrying about.

It's a darn powerful ultimate. But it's 5 mana and 4 more turns away. So it's allowed to be.

The comparisons with Tamiyo, the Moon Sage are natural. The cost and starting loyalty are the same; the +1s are both incredibly good; the [0] / [-2] are harder to use and not really the focus; the ultimates are very similar too. But this card's ultimate comes online one turn before Tamiyo's. Given how similar everything else is, I wonder if that's a good idea.

On the one hand, Tamiyo can protect herself against one creature, which this one can't. On the other hand, this is generating card advantage right from the word go. If you go straight to the ultimate, Tamiyo will have neutralised your opponent's best creature for 4 turns; this will have drawn you 4 extra cards. I feel they're at least comparable, and so the cost of this ultimate should probably match Tamiyo's.