Not only did the name mean "looking back at the past," it had a mechanic that referenced cards that had already been played
Structure Deck: Blue-Eyes White Destiny is a particularly good example for Blue-Eyes fans, as it is designed around that theme rather than leaving you to chase it randomly through packs
Dark Claw Speaking of Dark Claw, here it is
Its reported that there are only 31 known to exist
Karoo actually lets you produce more mana with the same number of lands by returning one of your Plains to your hand, and lands like Buried Ruin can help retrieve a mana rock or another key artifact lost early in the game
As a result, Aether Revolt will be one of the most interesting sets in years because it will contain not one but two card types (here, I'm counting energy as a card type, even though that's not technically correct) that are dangerous, and Wizards likely felt some amount of pressure to "top" Kaladesh with Aether Revolt