Detention Sphere | Magic: The Gathering
Formats Detention Sphere is Legal in
Official Oracle Text for Detention Sphere
When Detention Sphere leaves the battlefield, return the exiled cards to the battlefield under their owner's control.
Official Rulings for Detention Sphere
10/1/2012 : The enters-the-battlefield ability has only one target. The other permanents with that name aren't targeted. For example, a permanent with protection from white will be exiled if it has the same name as the target nonland permanent.
10/1/2012 : If the target nonland permanent is an illegal target when the enters-the-battlefield ability tries to resolve, it will be countered and none of its effects will happen. No permanents will be exiled, including those with the same name as the target.
10/1/2012 : If Detention Sphere leaves the battlefield before its enters-the-battlefield ability has resolved, its leaves-the-battlefield ability will trigger and do nothing. Then the enters-the-battlefield ability will resolve and exile the targeted nonland permanent and other permanents with that name indefinitely.