The Celestial Toymaker

Whenever The Celestial Toymaker attacks, look
at the top three cards of your library. Exile any
number of them in a face-down pile and the rest
in a face-up pile. Defending player chooses one
of those piles. Put that pile into your hand.
At the beginning of each end step, each opponent
loses 2 life for each spell or ability that caused
one or more players to guess or to group cards or permanents into a pile this turn.