The ability to return Cage of Hands to its owner's hand can only be activated if Cage of Hands is on the battlefield. If Cage of Hands is no longer on the battlefield when the ability resolves, Cage of Hands remains in its new zone and isn't returned to its owner's hand.
Random a card of Magic: The Gathering (MTG), but you can also roll the D20 dice, random a Planeswalker, have fun with the random rules and more.