Three of the official shortcuts deal with announcing or asking about choices before those choices need to be made.
If you cast a spell or activate an ability and declare choices that aren’t normally made until that spell or ability resolves, you have to abide by those declared choices unless another player responds to that spell or ability. For example, if you cast Memoricide by saying “Memoricide your Vengevines”, you have to name Vengevine when Memoricide resolves unless your opponent responds to the spell. In that case, you can name whatever card you like if and when Memoricide resolves.
If an opponent asks about choices that are made on the resolution of a spell or ability, that player is passing priority and allowing that spell or ability to resolve. For example, if you cast Journey to Nowhere and your opponent asks “Targetting?” He or she is allowing Journey to Nowhere to resolve and its triggered ability to be put on the stack, which is when you would declare a target for the trigger.
If a player casts a spell or activates an ability that would deal damage and chooses a planeswalker as a target for that spell, that player is really choosing that planeswalker’s controller and announcing his or her intent to redirect the damage to that planeswalker on the resolution of that spell or ability, and is held to that choice unless an opponent responds to that spell or ability.
For example, if you cast Lightning Bolt by saying “Bolt Jace” and pointing it at your opponent’s Jace, the Mind Sculptor with three loyalty counters on it, the Bolt will deal 3 damage to Jace unless your opponent responds. If your opponent responds by casting Steady Progress and proliferating another loyalty counter onto Jace, you can choose to have the Bolt deal 3 damage to your opponent (or another planeswalker he or she controls) instead of Jace.
Today’s Rules Tip was provided by Charlotte Sable, a level 2 judge from Ontario, Canada.