Guesswork

At the beginning of your upkeep target
player speculates. (Exile the top card of their
library face down. That player guesses if that
card has converted mana cost higher than four.
If that player chooses correctly, they put that
card into their hand and create a treasure token.)
You may cast one card each turn with
converted mana cost less than or equal to
the number of cards exiled with speculate.