Xerox, Chaos Angel

Xerox costs {1} less to cast for each card that has been Exiled this turn.
{t}{3}{w}{w}{w}{w}: Exile all Nonland Permanents on the battlefield, then return all of the Exiled creatures and artifacts to the battlefield under their owner's control.
{t}{3}{b}{b}{b}{b}: Look at a target opponent's Hand Exile 1 card from it , 1 card from your Deck, and 1 card from any Graveyard. During the next upkeep step, add all 3 cards to your hand.
{2}{w}{w}{w}{w}{w}{b}{b}{b}{b}{b}: Exile the top 25 cards of your deck,