One of the most hotly-debated cards in terms of flavor and story significance in Theros block is, of all things, Temple of Abandon. The red and green-mana-producing scryland is in theory the temple to Xenagos - except he doesn't become a god until Born of the Gods, and the card was printed in Theros. Among other things, the card also depicts an empty throne and a statue of an unknown god in the background. This has led some to theorize that there in fact was a red-green god before Xenagos, but this individual was killed, left in disgust, or otherwise is no longer part of the pantheon.
When zemyla asked Mark Rosewater on his Tumblr blog, "Did you mean to have the double meaning for "Temple of Abandon"?" Rosewater seemingly confirmed the theory:
Let’s say yes. : )
In this context, Abandon must mean both "hedonistic abandon," the frame of mind that Satyrs are typically in, and "abandonment," or, the fact that the previous god is gone. Whether this is actually carried through in Magic's canon in the storyline of Journey into Nyx remains to be seen, but the hints are probably too numerous and too well-defined to be red herrings. In other words, expect to see a third-act twist involving the lost god next set.