Yet another Trinisphere question...

[Esper3k]

So of course when someone tries to cast a spell under a Trinisphere, if they can't pay for the Trinisphere, they can't cast it and the spell just goes back to their hand (with probably a GRV warning in Competitive+ RELs).

However, what happens when someone tries to cast a spell under a Trinisphere, but forgets it's out, yet can actually pay for it? Are they allowed to do a taksie-backsie if they decide they don't want to pay for it or are they locked into the paying for it since they announced the spell? Does the REL of the event affect the answer?

As always, thanks for the answers!

[Tammit67]

As a level 1 judge, I'd be inclined to call this a Game Play Error- Game Rules Violation. Bolded emphasis mine.



Game Play Error—Game Rule Violation

Definition
This infraction covers the majority of game situations in which a player makes an error or fails to follow a game procedure correctly. It handles violations of the Comprehensive Rules that are not covered by the other Game Play Errors.

An error that an opponent can’t verify the legality of should have its penalty upgraded. These errors involve misplaying hidden information, such as the morph ability or failing to reveal a card to prove that a choice made was legal. If the information needed to verify the legality was ever in a uniquely identifiable position (such as on top of the library or as the only card in hand) after the infraction was committed, do not upgrade the penalty and reveal the information if possible.
Examples
A. A player casts Wrath of God for 3W (actual cost 2WW).
B. A player does not attack with a creature that must attack each turn.
C. A player fails to put a creature with lethal damage into a graveyard and it is not noticed until several turns later.
D. A Voice of All is on the battlefield that should have had a color named for it.
E. A player casts Brainstorm and forgets to put two cards back on top of his library.

Penalty
Warning

Philosophy
While Game Rule Violations can be attributed to one player, they usually occur publicly and both players are expected to be mindful of what is happening in the game. It is tempting to try and “fix” these errors, but it is important that they be handled consistently, regardless of their impact on the game.

Additional Remedy
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. Each action taken is undone until the game reaches the point immediately prior to the error. Cards incorrectly placed in hand are returned to the location in the zone from which they were moved (if the identity of the incorrectly drawn card is not known to all players, a random card is returned instead). Once the game is backed up, it continues from that point.

If not caught within a reasonable time frame, or backing up is impossible or sufficiently complex that it could affect the course of the game, the judge should leave the game state as it is after applying state-based actions and not attempt any form of partial ‘fix’–either reverse all actions or none, with the following exceptions:

•If a player made an illegal choice or failed to make a required choice for a permanent on the battlefield, that player makes a legal choice.

•If a player forgot to draw cards, discard cards, or return cards from their hand to another zone, that player does so.

•If an object changing zones is put into the wrong zone, the identity of the object was known to all players,
and it is within a turn of the error, put the object in the correct zone.

In a situation where the effect that caused the infraction is controlled by one player, but the illegal action is taken by another player, both receive a Game Play Error–Game Rule Violation. For example, if a player casts Path to Exile on an opponent’s creature and the opponent puts the creature into the graveyard, both players receive a Game Play Error—Game Rule Violation infraction.

Following this, we undo the casting of the spell entirely (backup to the point of the error) and give a warning to the player casting the spell if we catch the error upon casting.

If the error is caught further down the line when 'sufficient' other decisions have been made, then we do not back up and do not attempt to repair the game state. A warning for Game Play Error-Game Rules Violation will be given to the casting player and a Failure to Maintain Game state given to the opponent who let it happen. If the trinisphere is controlled by the opponent of the caster and the error is not caught immediately, both players receive Game Play Error—Game Rule Violation infractions as per the last paragraph

[barcode]

Players are never forced to pay costs (except in weird situations that don't apply here).

When you call a judge for your opponent casting Brainstorm (for example) with 4 Islands untapped and you with an untapped Trinisphere the judge will issue a GRV to your opponent, undo any mana costs paid thus far to pay for the Brainstorm, place the Brainstorm back in the hand and go from there.