Hey, I like this idea a lot. I miss heavy tribal themes, and love the idea of color-shifting Faeries into Green. IT would fit flavor nicely, and give a lot of sweet new interactions and options. Opening up green could also make Modern BUG Faeries a thing, which would be sweet!
As for what I'd like to see, on a
pure "card" level, I'd like to see the enemy colored Command cards (ex:
Atarka's Command,
Dromoka's Command,
Kolaghan's Command, but in the enemy colors R/W, G/U, B/W, G/B, R/U). I just think finishing the cycle could add a lot of power to decks that are close to existing as is.
on a more Flavorful level, I'd love a proper Angels vs. Demons block. G/W angels and R/B Demons, with blue playing both sides. I'm talking cheap costed angels and support, and cheap demons with amazing stats but real downsides. I miss the aspect of magic where the most powerful cards had downsides you had to work around, rather than the "Battlecruiser" style the top end has had lately.