Desmond, Rogue Infiltrator

Skulk (This creature can't be blocked by
creatures with greater power.)
When Desmond deals combat damage to a player,
look at the top four cards of that player's library,
exile one of them face down, then put the rest
on the bottom of that library in a random order.
You may cast that card for as long as it
remains exiled, and mana of any type
can be spent to cast it.