Sage Aven is a common Creature — Bird Wizard card from Onslaught (ONS), collector number 111. Current market price: $0.16 (foil $0.45), TCGplayer market prices via Scryfall.
Flying (This creature can't be blocked except by creatures with flying or reach.) When this creature enters, look at the top four cards of your library, then put them back in any order.