Master Warcraft
Instant
Cast this spell only before attackers are declared.
You choose which creatures attack this turn.
You choose which creatures block this turn and how those creatures block.
Zoltan Boros & Gabor Szikszai
Commander Anthology (CMA)
• #202Rulings
If a turn has multiple combat phases, this spell can only be cast before the beginning of the Declare Attackers Step of the first combat phase in that turn.
(wotc • 2013-09-20)
If the defending player controls a planeswalker, the person who cast Master Warcraft first chooses the complete group of creatures that are going to attack. Then, for each of those creatures, the active player chooses who or what it's going to attack.
(wotc • 2008-04-01)
You can decide that a creature won't block.
(wotc • 2006-01-01)
You choose attackers and make blocking assignments regardless of whether it's your turn and regardless of whether the creatures are attacking you. Your choices must be legal within the normal rules for attacking and blocking.
(wotc • 2005-10-01)
Rulings
If a turn has multiple combat phases, this spell can only be cast before the beginning of the Declare Attackers Step of the first combat phase in that turn.
(wotc • 2013-09-20)
If the defending player controls a planeswalker, the person who cast Master Warcraft first chooses the complete group of creatures that are going to attack. Then, for each of those creatures, the active player chooses who or what it's going to attack.
(wotc • 2008-04-01)
You can decide that a creature won't block.
(wotc • 2006-01-01)
You choose attackers and make blocking assignments regardless of whether it's your turn and regardless of whether the creatures are attacking you. Your choices must be legal within the normal rules for attacking and blocking.
(wotc • 2005-10-01)