Nice wagering and input from all concerned. Of course that particular matchup is one of many possible combinations. In the preview of game 2, the full list of recommended/suggested nations (and pretenders) for each team are ordered by native casting ability in Nature (secondarily Earth), Blood, Death, and Astral.
Looking at the nations one does see commonalities and common themes which make grouping teams by them certainly possible and quite interesting. I know I will have fun watching these forces go at each other. A lot of fun!
And this fiendish delight will be increased by each team not having the same "toolkit" as it were, to work with. For the Arboreans, all of the following MA nations have native nature mages (not just random picks):
Pangaea, Man, Eriu, Mictlan, Machaka, C'tis, Bandar Log,
Shinuyama, T'ien Chi'.
Arboreans also have a good bless in that the nature and earth blesses are supposedly the most useful.
Also interesting is the common theme that emerges and that is embodied in the team proposed for game 3, Collegium Arcanum. Some nations, such as T'ien Chi', Arco, and Shinuyama are so diverse and versatile in their spell casting ability that they fit the Collegium's rainbow theme quite nicely. Aside from the rainbow pretenders, there are SC pretenders with native casting ability in 3 and sometimes 4 different paths.
There are many possibilities to explore the full worth of each and every nation and many ways to enjoy the game, which is probably what Gandalf was speaking about. Playing blood only games (or other path based games) and role playing is one such way. I'm not an expert on nature magic, but I'd imagine in the hands of those who know how to use it best, it can be quite effective. Even those nature tunes/songs are useful.
Keep in mind that unless I specify exactly which nations are available to each team (pre-set the nations), the team theme can be met by any combination of nation or pretender choice. So there's plenty of flexibility.
Of course one can group by other things (excluding water nations), if someone can come up with 4 common themes that aptly describe them and their associated pretenders, be my guest. Go through all the MA nations and pretenders and tell me what you come up with. How many giant nations are there in MA? What size level = giant, 3, 4, 5, 6? Are there not problems with Hinnom and Ashdod on the same team as it stands? How many "human" nations are there?
Again, it is for fun, and for those who wish to role play a bit. Thanks for all the responses, keep em coming.