Scenario:
It is Adam's turn. Nick control's Thalia, Guardian of Thraben.
Adam casts Brainstorm and pays a single blue mana to cast it. Nick says okay and lets the spell resolve. Then judge is called.

The question here is whether this is a double GRV, of if Adam receives a GRV while Nick receives FtMGS.

To quote the IPG:
“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.”


does “effect” cover continuous effects (static abilities) in this case?

I would say it's double GRV. FtMGS is defined as allowing another player to commit a GPE involving an effect or action they he or she doesn't control. I think that pretty clearly rules out the effect of Thalia.

No it would only be a GRV for Adam, and a FtMGS for Nick. Static abilities don't have a controller, only objects on the stack or the battlefield have controllers.

Originally posted by Cris Plyler:

Static abilities don't have a controller, only objects on the stack or the battlefield have controllers.

While the rules define who control “objects”, the MIPG does say the following…

“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.”

…and if we want to be really, really technical, there is nothing in the rules that define “effects” as being controlled by anyone.

So, I think it is fair to say that Nick's control of Thalia does make him more culpable in this situation and that he does need to have more awareness of the ability and its potential impact on Adam's actions. In that respect, I would agree with Mr. Hubble's opinion of GRV for both players in this situation. While we could technically parse the MIPG, I think this situation generally fits the clause above.

The example given in the IPG–“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.”–is as far as I can recall, the common error at the time that led to this clause being added. It's a case of “my card, your error” that led to some rather odd discussions about who gets the GRV and who gets the Ftmgs. It's the resolution of A's spell, so he or she certainly carries some culpability, but B is also responsibly for carrying out the physical actions incorrectly. They are both “doing” something wrong.

I feel that Thalia is different. Here, B is casting a spell incorrectly. He or she is “doing” something wrong. A is “letting” something wrong happen, and that is classic Failure to Maintain Game State to me, the same as if B had cast a spell wrong for no particular reason (tapping 3W for Wrath of God) or forgetting to pay for his or her own Thalia. Double GRV should only happen when both parties are active participants in the error rather than passive.

Originally posted by Riki Hayashi:

I feel that Thalia is different. Here, B is casting a spell incorrectly. He or she is “doing” something wrong. A is “letting” something wrong happen, and that is classic Failure to Maintain Game State to me, the same as if B had cast a spell wrong for no particular reason (tapping 3W for Wrath of God) or forgetting to pay for his or her own Thalia. Double GRV should only happen when both parties are active participants in the error rather than passive.

Well, how is that really different from the Path to Exile example then? You putting the creature in your graveyard is an action, but if I let you do it, then I'm being passive in that situation. I'm “letting” that action take place, even though it is wrong. In that respect, I don't quite agree that “level of activity” or somekind of “activity versus passivity” is the metric here.

But my feeling was that we wanted to distinquish more from situations where Player A was violating an actual game rule (such as putting a 3/3 into the graveyard even though it only had 2 damage marked on it) and Player B overlooks that violation. In that respect, I see the “amount of participation” in the situation, where Player A's action is impacted (or should be impacted) by something that Player B has done to affect the current game state.

In essence, it becomes a bit of contributory negligence. Player A may be at fault, but Player B has contributed to make that fault possible.

It's the resolution of A's spell. A should always be responsible for his or her spell's actions being carried out correctly regardless of who is doing the physical actions.

Originally posted by Riki Hayashi:

It's the resolution of A's spell. A should always be responsible for his or her spell's actions being carried out correctly regardless of who is doing the physical actions.

Both players are always responsible for making sure that objects resolve correctly regardless of who controls the object. The discussion is about the degree of responsibility.

Scenario:
When it is Player A's turn, he makes a play that, from looking at just his side of the board, should be legal (casting brainstorm for U). It turns out that it is not legal because of something Player N controls.

Is player N responsible for making sure his card's effect is remembered? Yes.
Is player N more responsible than normal because it's his card that changes the game? Sure.

Is he responsible to the point of GRV? That is the tricky part. I'm inclined to say yes.

This line makes sense:
When you play a card with an effect, you are responsible to see that the effect is applied correctly.

How about this next line:
You can receive a warning for a GRV if your effect is forgotten and that causes a game rule violation.

Seems to me, the first sentence of FtMGS pretty much covers it: A player allows another player in the game to commit a Game Play Error involving an effect or action that he or she does not control, and has not pointed it out immediately.

Apply that to Thalia may be a bit of a stretch (and certainly, Riki's logic is sound), but the happy result is that it discourages gaming the system. Thalia is good - even very good - but being able to FtMGS her to an opponent's disadvantage is simply TOO good, IMO.

And yes, Path to Exile is certainly the poster child for “both players get GRV”.

I will point out that it's probably (usually) approaching irrelevant, if it's an honest mistake. Whether you award GRV or FtMGS to Thalia's controller, for the opponent's mistake, the message to that player should be clear: pay more attention! And, like other infractions, even a FtMGS, when done intentionally to gain advantage, is a Very Bad Thing.