the way that Niv is going to get the guilds to work together is putting them into a D&D maze and forcing them to work together, creating tri colored cards!!
If you look at all the past walkers they have a certain detail when it comes to art work. I'm betting this walker is Gruul because of the pictures revealed by wizards. Its the woman who has a type of war paint on, only shows her head, but the right detail is there.
What do you think about Ajani being elevated to White/Red/Green? It would make sense that he would be able to wield the colors of mana from his home plane.
This article makes it interesting. If Niv could harness the power of these "leylines" in ravnica he would have a maze.
RGD
and
RGD
the three sets in both blocks correspond?
weird