Mirrodin

Timesifter

At the beginning of each player's upkeep, each player removes the top card of his or her library from the game. The player who removed the card with the highest converted mana cost takes an extra turn after this one. If two or more players' cards are tied for highest cost, the tied players repeat this process until the tie is broken.

At the beginning of each upkeep, each player exiles the top card of their library. The player who exiled the card with the highest mana value takes an extra turn after this one. If two or more players' cards are tied for highest, the tied players repeat this process until the tie is broken.