Master of Diversion

• WWizards of the Coast2013-07-01
  Official Ruling
  In multiplayer formats, including Commander, only a creature controlled by the defending player Master of Diversion is attacking can be chosen as the target, even if your other attacking creatures are attacking different players.
• WWizards of the Coast2013-07-01
  Official Ruling
  The ability will resolve and the creature will become tapped before blocking creatures are declared.

Rulings via Scryfall