The set was about giant fighting machines. This meant the two major mechanics wanted to go on artifacts. When this happens in a set (the thematic focus wants to be on permanents), it's common for the Set Design team to make a splashy rare spell cycle.

Commands (choose two from four options) first appeared in Lorwyn and have proven to be popular with the players, so we've done many versions. We hadn't done a monocolor cycle since their premier, though, so the Set Design team thought about adding them. The big question was how do you make them feel like they belong here in this set? Once the idea came up that each one would represent a specific character from the story (white, Kayla; blue, Urza; black, Gix; red, Mishra; and green, Titania), the cycle came together.