Atari is playing against Nintendo on Day 1 of a Grand Prix. Atari casts a Chrome Mox. Nintendo nods, and then says, “When it enters the battlefield I’ll cast Wear (from Wear // Tear) on it.” Atari taps Chrome Mox and casts Brainstorm in response. Nintendo calls a judge (you), and explains that Atari tapped the Mox for mana without imprinting anything on it. Atari says, “Oh, okay. I guess it’s too late for me to imprint anything?”

What do you do? What are the appropriate infractions and penalties (if any)? How do you fix the situation?

Judges, feel free to discuss this scenario on Judge Apps!

[expand title=Answer]Thank you to everyone who took part in this week’s Knowledge Pool scenario!

In our scenario, atari tapped her Chrome Mox before resolving the imprint triggered ability, which is perfectly legal. However, she cast Brainstorm as if it had made blue mana, when in fact it made no mana at all – and that’s a Game Rule Violation, for which she should receive a Warning. Because Nintendo pointed out the error immediately, there should be no Failure to Maintain Game State Warning issued to him.

Now, there’s the issue of a fix. The IPG gives us some direction:
If the error was discovered within a time frame in which a player could reasonably be expected to notice the error and the situation is simple enough to safely back up without too much disruption to the course of the game, the judge may get permission from the Head Judge to back up the game to the point of the error.

The point of error is casting Brainstorm without the mana to pay for it. Since nothing has happened since that action, we can easily back up by putting the Brainstorm back in Atari’s hand. After the fix the gamestate looks like this: Wear // Tear is on the stack targeting the Chrome Mox, with the Imprint trigger underneath it. The head judge does have the option to leave the game state as is, but the situation in this case is simple enough that we recommend the rewind.[/expand]