L'Cherr, the Masked Carnival

When L'Cherr, the Masked Carnival enters the
battlefield, for each player, look at the top five
cards of that player's library and exile a creature
from among them face down. Put the rest on the
bottom of that player's library in a random order.
{0}: Reveal a card exiled by L'Cherr. L'Cherr
becomes a copy of that creature until end of
turn. Activate this ability only once each turn.