Arkhos, twilight zone

—During your upkeep, roll a d20 :
1 : You may play the top card of your library without playing its mana cost.
2 - 5: Draw a card.
6 - 9: You gain 1 life.
10 - 15: You loose 1 life.
16 - 19: Discard a card.
20 : Sacrifice a permanent.