Part of the MTR regarding Tournament Shortcuts is this:
“If a player casts a spell or activates an ability and announces choices for it that are not normally made until resolution, the player must adhere to those choices unless an opponent responds to that spell or ability. If an opponent inquires about choices made during resolution, that player is assumed to be passing priority and allowing that spell or ability to resolve.”
My question is how exactly this applies to searching for cards and how it applies to illegal choices. If a player casts a spell with Bolster 1 and says “put a counter on this Bear Cub” and they control that Bear Cub and a 3/3 they are bound to that choice. But what if the player controls the Bear Cub and a 1/1. The game obviously wouldn't end up with the counter on the Bear Cub. Does the player commit an infraction as soon as they make that announcement or when they actually put the counter on the creature on resolution? What if the player says that they'll put the counter on a land they control or a planeswalker?
Does this rule also apply to searching your library? Say a player casts Search for Tomorrow, says “I'll get a forest”, their opponent lets it resolve and then the player searches up a Mountain to cast a Lightning Bolt. What if the Player genuinely doesn't have any Forests left in their deck?

Originally posted by Martin Hergeth:

If a player casts a spell with Bolster 1 and says “put a counter on this Bear Cub” and they control that Bear Cub and a 3/3 they are bound to that choice.

Not so much bound to that choice as there just isn't any other legal outcome.

Originally posted by Martin Hergeth:

But what if the player controls the Bear Cub and a 1/1. The game obviously wouldn't end up with the counter on the Bear Cub. Does the player commit an infraction as soon as they make that announcement or when they actually put the counter on the creature on resolution?

Players can “bluff” - i.e., make a statement about a false or impossible future. Players can't perform illegal actions. Until an illegal action occurs, there is no infraction - so claiming you're about to commit an infraction is not, in itself, illegal.

Originally posted by Martin Hergeth:

Say a player casts Search for Tomorrow, says “I'll get a forest”, their opponent lets it resolve and then the player searches up a Mountain to cast a Lightning Bolt.

The specific land the player intends to get is not something that has to be announced - technically, that rules text says “search for a card with the quality ‘Basic Land’”; it does NOT say “name a Basic Land, then search for that land”. So they can cast Search for Tomorrow, Rampant Growth, or even Farseek, say “I'm gonna get a Wastes” - and then proceed to resolve the spell correctly. (Again, if they actually resolve it incorrectly, that's an infraction - not the “bluff” that precedes the infraction.)

Originally posted by Martin Hergeth:

What if the Player genuinely doesn't have any Forests left in their deck?

This is not a factor, and we should not endeavor to confirm this hidden information. After all, this is a search for a card that matches a quality, so it's legal to fail to find a card, even if one or more is still in the library. Whether or not they have any Mountains left is private information - i.e., the Player Communication policy in the MTR allows a player to lie about that information, and the judge should never attempt to confirm or correct such a bluff.

d:^D

Originally posted by Scott Marshall:

Originally posted by Martin Hergeth:

If a player casts a spell with Bolster 1 and says “put a counter on this Bear Cub” and they control that Bear Cub and a 3/3 they are bound to that choice.

Not so much bound to that choice as there just isn't any other legal outcome.

Originally posted by Martin Hergeth:

But what if the player controls the Bear Cub and a 1/1. The game obviously wouldn't end up with the counter on the Bear Cub. Does the player commit an infraction as soon as they make that announcement or when they actually put the counter on the creature on resolution?

Players can “bluff” - i.e., make a statement about a false or impossible future. Players can't perform illegal actions. Until an illegal action occurs, there is no infraction - so claiming you're about to commit an infraction is not, in itself, illegal.

My examples were bad, what I meant was that if a player says they are going to make a certain legal choice as they are casting the spell, they are bound to that choice. A better example would be a Bolster 1 card while they had 2 2/2 creatures in play. If they say something like “I'll bolster my Bear Cub” while casting it and the opponent doesn't respond, they are bound to that choice. But if I understand you correctly, that only applies as long as the announced choice is legal and not searching for a card?

Originally posted by Martin Hergeth:

But if I understand you correctly

Well, I'm not certain that's the case. The point I'm trying to make is that you may be extending the “makes a choice prior to resolution” too far, applying it to things that aren't actually announced as choices.

The card that inspired this policy is Persecute; the “Jedi Mind Trick” that some players were attempting was to say “Persecute for Red” when announcing the spell, waiting for the opponent to pass priority (because, apparently, they don't have any Red Instants to respond with) - and then naming a different color on resolution.

If Search for Tomorrow (et al) said “Name a Basic Land. Search your library for a card with that name and…” - that'd be a choice normally made on resolution, and that part of the shortcuts policy would apply. It doesn't say that, and that policy does not apply.

d:^D

Originally posted by Scott Marshall:

The card that inspired this policy is Persecute; the “Jedi Mind Trick” that some players were attempting was to say “Persecute for Red” when announcing the spell, waiting for the opponent to pass priority (because, apparently, they don't have any Red Instants to respond with) - and then naming a different color on resolution.

I think Martin is trying to ask what the ruling would be if a player says “Cast Persecute naming colorless” in an attempt to skirt modern shortcut rules and pull the same Jedi Mind Trick.