For example, your opponent couldn't cast Sudden Edict targeting you, but you'd still have to sacrifice a creature if they cast Innocent Blood
We took the traditional design for playing cards which is in the public domain, redrew the card faces completely making the design unique to the MPC brand
Honorable Mentions Kinjallis Caller / Otepec Huntmaster / Intrepid Paleontologist Dinosaurs, being apex predators in their day, are rather expensive when it comes to casting them for full mana value in Magic
It's not very hard to break it, of course -- just add in Phyrexian Arena and/or Pitiless Plunderer and that pesky mana requirement is resolved -- but at least Kels completely broken all by itself like Korvold, Fae-Cursed King
Nearly half of Battle for Zendikar has been spoiled at the time of writing and one thing is clear: Wizards of the Coast wants us to play with expensive and awesome Eldrazi creatures the same way we did during the era of Rise of the Eldrazi