A player allows another player in the game to commit a Game Play Error and does not point it out immediately.
There are actually several things going on here. The first is that a player committing a Game Play Error can never earn Failure to Maintain Game State. The only person that can get Failure to Maintain Game State is the opponent. A player earns Failure to Maintain Game State when they do not catch an error made by the opponent. Also note that if a player points out the opponent’s error right away, they do not earn this infraction. For example, if Abe casts Wrath of God for RRRW and Ned notices before any further actions are taken, Ned will not receive Failure to Maintain Game State.
If a judge believes a player is intentionally not pointing out other players’ illegal actions, either for their advantage, or in the hope of bringing it up at a more strategically advantageous time, they should consider an Unsporting Conduct — Cheating infraction.
Generally we think of Cheating as actively and intentionally doing something against the rules and for an advantage. However, it may also also be Cheating to notice your opponent doing something against the rules and not call a judge, or to only call a judge when it is to your advantage. For example, Abe controls a Juggernaut and forgets to attack with it. Ned says nothing, because he doesn’t want to take the damage. Depending on Ned’s knowledge of game rules and player responsibilities, this may be Cheating.
Not reminding an opponent about their triggered abilities is never Failure to Maintain Game State nor Cheating.
This is a very important exception to the “you must point out your opponent’s errors” rule. Missed triggers are handled differently. A player is allowed to not point out their opponent’s missed triggers. Since it is allowed, it cannot be an infraction. See the Missed Trigger section for more details.
- A. A player’s opponent forgets to reveal the card searched for by Worldly Tutor. It is not noticed until the end of turn.
- B. A player does not notice that his opponent has Armadillo Cloak on a creature with protection from green.
In both of these cases, the player’s opponent committed a Game Rule Violation, and the player didn’t notice it right away.
If an error is caught before a player could gain advantage, then the dangers of the ongoing game state becoming corrupted are much lower.
This is really just a fancy way of saying “the sooner an error is caught, the less likely it is to cause a large problem.” It should be a fairly obvious statement.
If the error is allowed to persist, at least some of the fault lies with the opponent, who has also failed to notice the error.
The key point here is that both players are responsible for the game state. If the opponent is being observant, they can help catch a player’s error before the problem becomes more severe. It doesn’t matter who gained an advantage from it. Note that there are some situations where one player controls the effect, and the other player takes the action, but did so in a way that caused an error. In this case, please refer to the Game Rule Violation section, as there are some cases where both players have committed the same infraction.