Nekusar, Reaper of Sanity

Menace
Whenever a creature you control deals damage to
a player, reveal the top card of that player's
library. If the top card is an Instant or Sorcery
card, you can cast it without paying it's mana cost.
If a card is revealed and not cast this way, put it in
its owner's graveyard.
{t}: Search target opponent's library for a card and
exile it. That player shuffles their library and you
put the exiled card second from the top of their
library.