You are the Head, and only, judge at a Theros/Khans of Tarkir Standard Grand Prix Trial. Nilva controls three white 1/1 Soldier tokens. At the end of Arridor’s turn, Nilva casts Stoke the Flames by tapping his three tokens and a Mountain and targets Arridor. Arridor and Nilva mark the life total change on their life pads and Nilva puts the Stoke the Flames in his graveyard. Arridor looks at his hand, then at the board, and then realizes that Nilva could not cast Stoke the Flames and did not have another red source available and calls a judge.

What do you do?

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[expand title=Answer]In this scenario, Nilva has cast Stoke the Flames with an incorrect cost and lacks the second red mana source or a red creature to tap via Convoke to pay for the spell. Nilva has committed Game Play Error – Game Rule Violation and will receive a Warning. The mistake should then be fixed with a back-up of everything that happened until just prior to the casting of the Stoke the Flames. Revert Arridor’s lifetotal to the previous total, untap the three tokens and the single Mountain, and return Stoke the Flames to Nilva’s hand.

While it is always up to the judge’s discretion, we do not feel that enough happened after the error for Arridor to receive Game Play Error – Failure to Maintain Game State because he has pointed out the error in a reasonable amount of time. If Arridor had allowed Nilva to continue to untap and start his turn, or take other actions before pointing out the error, then we would assess Failure to Maintain Game State to Arridor. Instruct the players to continue playing, issue an appropriate length time extension if the ruling took more than a minute, and record the penalty on the match slip.[/expand]