Think about how the print process has to change if a new unique mechanic alters our perception of a normal magic card
Moments like Nahiri's revenge on Sorin, Liliana's alliance with the Gatewatch, and Emrakul's self-inflicted sealing have all gone down in Magic: The Gathering history.
Jungle Holos have crept upward as the surviving supply thins out, a played copy now runs in the high $30s, with cleaner examples climbing into the $40s and beyond
That gives us bird powerhouses like Derevi, Empyrial Tactician, Falco Spara, Pactweaver, and the bird of birds, Birds of Paradise provides us with access to birds-matter staples like Soulcatchers' Aerie, Flurry of Wings, and Tawnos, the Toymaker and, of course, green brings some of the best land ramp and landfall cards, with staples like Scute Swarm and Tatyova, Benthic Druid: And that's just looking at existing cards Final Fantasy has a good chunk of new bird and landfall toys to play with
The most critical part of the rules on Shift is what happens to the original card and more importantly what happens to the original when the top card is affected by something
So lets look at which are fetching the highest prices, and why