Originally posted by Todd Bussey:
Is it the controller of Blind Obedience's responsibility to alert his opponent? (similar to a trigger)
Or if both players forget initially, does Obedience's controller have any recourse?
The general rule on “shared responsibility” applies. We make an exception involving an opponent's responsibility to alert a player to his or her own triggers, but that is an exception to the general requirement. Both players still do have responsiblity to make sure the game rules are followed.
Typically what will happen is the opponent will put the creature onto the battlefield untapped, and Blind Obedience's controller will point out the effect. The opponent taps the creature, and life moves on. Technically a game rule was violated (albeit briefly), but the players fixed it without any major repercussions. It might even be discovered after another spell is cast, in which case the players may fix it themselves (especially if they view it as clerical and the creature being tapped/untapped has nothing to do with the spell being cast) or they may call a judge.
Where a judge usually becomes involved is when “significant” time has passed since the error was made, and the player is now making a decision that is affected by this error. Such as when declaring attackers and realizing the opponent has an extra potentially blocker.
Originally posted by Todd Bussey:
Can he call a judge to get the offending artifact/creature tapped?
Would they both get warnings via section 2.5 of the IPG?
In all cases, a player who notes a mistake should call a judge. After that, it is up to the judge to investigate to determine what infraction, if any, has occurred. Once a judge has decided an infraction has taken place, he or she handles it according to the MIPG. Such a situation where the opponent accidentally didn't account for the replacement effect generated by the other player's permanent is going to be GPE-GRV for both players (as you correctly observe) and so both should be issued a Warning. (Edit: One caveat is that if the Blind Obedience's controller calls a judge immediately when the error happens, I'm likely to only conclude the opponent committed GPE-GRV; the controller did his due diligence in calling for a judge as soon as the error happened.) The decision to back up or not is going to be up to the individual judge, with the permission of the Head Judge.
Edited Brian Schenck (Jan. 28, 2013 12:24:56 PM)