Predavyr, Master Thief

Whenever you gain control of a permanent an opponent controls, you get an experience counter.
At the beginning of your upkeep, look at the top X cards of target player's library, where X is the
number of experience counters you have. Exile a card from among them face down, and put the rest on the bottom of that library in a random
order. You may look at and cast that card for as long as it remains exiled, and you ma