You sacrifice flying creatures but you get to do more things with your own creatures on your turn, and bouncing cards of theirs with Man-o'-War and Tradewind Rider could deal with things you don't want to give to other players but don't want the original player to have, either
They come in the same four rarities that MTG cards do (common, uncommon, rare, and mythic), and you can spend one wildcard to craft/print any one card of the same rarity
What Are the New Cards in Quick Draw
Cards with high-volume sales often compete with one another for search visibility on auction sites
Then, for the rest of your turn, an ability used by any planeswalker with that type gets copied
I know a guy who spent $3,500 on an Ebay collection based on pictures of a handful of "random" pages from several binders