Set Theme Game

Nivix Echocaster
Creature - Human Wizard
Unthink (You may exile instant and sorcery spells you control as they resolve.)
, : Until end of turn, you may cast a card exiled by Nivix Echocaster. (You still pay its costs.)
3/2

Note: Tapping this allows you to only cast one spell, not multiples. The timing restrictions still apply, so sorceries only during your main phase.

lizstar: I want so very badly for this to be an actual mechanic, so I can play this whenever it triggers.

I'm not sure if Supercharge works as written, since you technically couldn't determine if the choice had been made until the next untap step came up. You could do it with exerting the lands, but that didn't exist as a mechanic at the time. So I think you'd have to word it as something like, "When you cast this spell, you may choose to have any lands that produced the mana for this spell not untap during your next untap step."

Even then, though, there's some inherent weirdness in how this works. First of all, in what happens if you use only nonland sources to produce mana, since there's technically nothing to stop that. You would choose not to untap the lands used, which is no lands, and the condition would still be met. Also, this means weird interactions with cards that interact with the mana pool (which is still a thing, even though cards don't reference it any more). For instance, if a card prevents mana from emptying from the pool, does that mana maintain its source into subsequent turns, does it come from the card that made it not empty, or does it cease to have a source? What about cards like Kruphix, that change the mana in your pool - does that mana still come from its original source, from the card that changed it, or nowhere? Despite there being situations where this information would be important already, the Comprehensive Rules don't cover either of these (unless one considers the specific case handling for Power Drain to be a universal ruling, which I do not, as it is clearly written to address the specific mechanics that one card). If they do keep their original source, that creates more confusing bookkeeping, especially in the case of carry-over mana.

challenge specified multicolor

Gonna judge this tomorrow everyone!

Hi Everyone, sorry for the very late reply. A family member got a terminal diagnosis this past week so I've been out of the loop here.

I'm gonna call Flo00 on this one.

Sorry again for the long delay.

crimsonreaper - Condolences on the unfortunate news.

Flo00

I think you missed something, actually. Being "whenever" rather than "if" does make it create multiple tokens. Annihilator will require multiple permanents to be sacrificed. Then, for each one, you have the choice to either let it be sacrificed, or create a spawn.