Jezzirra, Bane of Crymea

At the beginning of each player's upkeep, create
a black and blue aura enchantment curse token
named Curse of Thought Scour and attach it to
that player.
{u}{b}{g}, Sacrifice all curses you control attached
to target player: Exile the top X cards of that
target player's library, where X is the number
of curses sacrificed this way. You may play the
exiled cards until end of turn.