Kylyn, Dimir Polymorphist

Kylyn enters the battlefield with X +1/+1 counters.
Remove a +1/+1 counter from Kylyn: Choose one- -Target creature becomes a copy of another target creature until end of turn.
-Target player puts the top five cards of your library into his or her graveyard.
{u}{b}: Put a +1/+1 counter on Kylyn.