Portal Mage

Flash
When Portal Mage enters the battlefield during the declare attackers step, you may reselect which player or planeswalker target attacking creature is attacking. (It can't attack its controller or its controller's planeswalkers.)

Flash
When this creature 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.)

Commander Masters

Flash
When Portal Mage enters the battlefield 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.)