When a commander is destroyed and I play a card to exile, will it be exiled from the game permanently or can a opponent still cast his commander
When a Commander/General is exiled, the commanders owner has the choice of leaving the commander in exile or returning him to the command zone as if it died (along with the +2 colorless cost to cast again). If you leave him in exile, I believe the rule is that you make this decision again at each upkeep, whether or not to keep him exiled. Could be wrong about when you get to choose again, but I know it's at a regular interval, at least once during each of your turns if not all turns.
In case anyone wonders why you'd want him to stay exiled, it's for situations like when he gets hit with {oblivion ring} and you have something handy to kill enchants, like {austere command}.
Alright thanks