Sistian, the Generous

At the beginning of each player's upkeep, that
player exiles the top card of their library. They
may play that card this turn.
Whenever a player plays a card from exile, put a
+1/+1 counter on Sistian, the Generous and
you gain 1 life.
{g}{u}, Remove a +1/+1 counter from Sistian:
Target creature gains hexproof until end of
turn.