Misleading Signpost (FDC) from Foundations Commander, available at 401 Games Canada.

• Rarity: Rare
• Finish: Normal
• Artist: Julian Kok Joon Wen
• Card Text:
  Flash
  When this artifact enters during the declare attackers step, you may reselect which player or permanent target attacking creature is attacking. (It can't attack its controller or their permanents.)
  T: Add U.