While this concept of a serialized card isn't new for Magic, cards with very limited printing with each copy uniquely numbered, with arguably the most well-known offering being the 1 of 1 The One Ring from the Lord of the Rings set a few years ago
Fantasy Flight says that the one-action structure - similar to that used in Destiny - means players can quickly respond to their opponents moves, with the timing of card actions playing a big part in the outcome of matches
Cards of this type keep other characters from being challenged, stepping out in front to shield them
Tom LaPille had worked on a Duel Masters set right before being on the Innistrad design team, and when we were looking for a solution to making cool Werewolves, he suggested the double-faced technology that the Duel Masters team was using
Simic Ascendancy, gives me a mana sink that makes my big creatures scarier, plus an alternate win condition