Saloon Fiend

At the beginning of each player's upkeep, that
player reveals the top card of their library. They
may put that card into their hand. If they do,
they lose life equal to it's mana value. Otherwise,
they put that card into their graveyard.
Whenever a spell or ability you control causes an opponent to lose life, put a +1/+1 counter on
Saloon Fiend. It gains first strike until end of
turn.