At a Competitive REL Legacy event Nightingale controls Blood Moon. Annabelle casts Leyline of Sanctity by sacrificing two Lotus Petals for WW and tapping City of Traitors for 2. In response, Nightingale casts Lightning Bolt targeting Annabelle and both spells resolve normally. Annabelle then plays an Island and sacrifices the City of Traitors. After Annabelle puts her City into the graveyard, Nightingale realizes that Blood Moon affects City of Traitors and calls for a Judge. After investigating, you conclude that this was an honest mistake.

What do you do?

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

[expand title=Answer]This would be a Game Play Error – Game Rules Violation for Annabelle and a Game Play Error – Failure to Maintain Game State for Nightingale since she let Annabelle tap the City of Traitors for 2 mana instead of 1 and did not point it out immediately. As the Head Judge, you decide whether or not to rewind – some will choose to rewind and some will not.

We suggest to take into account the following key concepts before evaluating a backup:
– decision points; if players are likely to change their decisions after a rewind, it’s disruptive.
– damage to the game state should be less after a rewind than if we left it as is.

If you believe the situation is simple enough to safely back up without too much disruption and choose to rewind, you would back up the game state to where Leyline of Sanctity would be cast which would include putting the City of Traitors back on the battlefield, returning the Island back to Annabelle’s hand, untapping Nightingale’s land, putting the Lightning Bolt back into her hand, returning the two Lotus Petals back onto the battlefield and putting the Leyline of Sanctity back to Annabelle’s hand.

Remember that when there is an error when casting a spell and we think that it is okay to rewind, we back up the entire process and not just to the point of error. So instead of rewinding back to where she announces that she puts the Leyline of Sanctity on the stack, we rewind it all the way and put the card back into her hand.

Why is it not a GRV-GRV? The definition of a Game Rules Violation states that “If a player takes an action controlled by his or her opponent, but does it incorrectly, both players receive a Game Play Error – Game Rules Violation”. Blood Moon is not one of these effects, as it does not require Annabelle to take an action controlled by Nightingale, so it is NOT a GRV-GRV and is instead a GRV-FtMGS.

Why are we giving a GRV for insufficient mana? While the basic rewind is covered in the comprehensive rules under CR 717.1 (“Handling Illegal Actions”), we are still giving the penalty because they did violate the rules of the game – in this case casting Leyline of Sanctity for 1WW instead of 2WW.
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