Flying (This creature can't be blocked except by creatures with flying or reach.)
Whenever Thieving Aven deals combat damage to a player,
heist target opponent's library
(Look at three random nonland cards in target opponent's library and exile one face down. You may cast that card for as long as it remains exiled, and mana of any type can be spent to cast it.).
Whenever you cast a spell you don't own, put a +1/+1 counter on Thieving Aven.