The Dead Shall Serve

• WWizards of the Coast2010-06-15
  Official Ruling
  If, during your declare attackers step, one of these creatures is tapped or is affected by a spell or ability that says it can’t attack, then it doesn’t attack. If there’s a cost associated with having that creature attack, you aren’t forced to pay that cost, so it doesn’t have to attack in that case either.
• WWizards of the Coast2010-06-15
  Official Ruling
  If there are multiple combat phases in a turn, each of these creatures must attack its owner in each of them that it’s able to.
• WWizards of the Coast2010-06-15
  Official Ruling
  If one of these creatures can’t attack its owner during any given turn (due to a spell or ability such as Chronomantic Escape, or because a player on the opposing team has gained control of it, for example), it may attack another player, attack a planeswalker an opponent controls, or not attack at all. If there’s a cost associated with having that creature attack its owner, you aren’t forced to pay that cost, so it may attack another player, attack a planeswalker an opponent controls, or not attack at all.
• WWizards of the Coast2010-06-15
  Official Ruling
  Each of the creatures you put onto the battlefield this way must attack its owner, not a planeswalker that player controls.
• WWizards of the Coast2010-06-15
  Official Ruling
  For each opponent, you may choose not to target any creature cards in that player’s graveyard.

Rulings via Scryfall