Malfestio, Nightcloaked

Flying, hexproof
When Malfestio enters the battlefield, exile the
top card of each player's library face down with
a nightcloak counter on it. You may look at cards
with nightcloak counters for as long as they
remain exiled.
{1}{u}, Reveal a card with a nightcloak counter:
Counter target spell that shares a card type with
the revealed card.