Rotted Ones, Lay Siege

• WWizards of the Coast2010-06-15
  Official Ruling
  Each of these Zombies must attack its designated player, not a planeswalker that player controls.
• WWizards of the Coast2010-06-15
  Official Ruling
  If there are multiple combat phases in a turn, each of these Zombies must attack its designated player in each of them that it’s able to.
• WWizards of the Coast2010-06-15
  Official Ruling
  For each Zombie token you put onto the battlefield this way, make sure it’s clear who its designated player is. A token’s designated player won’t change for the rest of the game.
• WWizards of the Coast2010-06-15
  Official Ruling
  If one of these Zombies can’t attack its designated player during any given turn (because that player has left the game, 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 with having that creature attack its designated player, 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
  If, during your declare attackers step, one of these Zombies 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.

Rulings via Scryfall