Keros, Scarred by Time

+2: Flip a coin. If you win the flip, take an extra turn after this one. If you lose the flip, sacrifice Keros, Scarred by Time.
+1: Tap target permanent. That permanent doesn't untap during its controller's next untap step.
0: Reveal the top card of your library. If it's a blue instant or sorcery card, put it into your hand.