I'm in the very early stages of developing a block on the custom plane of Ruckmoor. It's "wedge"- or "alliance"-based. This topic is, obviously, for the community-aided development of the plane and block.
Eons ago, Ruckmoor was an average plane with agreements and disputes between each and every color. However, that gradually changed over those Eons. The first major change was the formation of ten loose affiliations between the colors, five allied pairs and five enemy pairs.
Several millennia after the allies gathered, an enemy pair associated itself with an allied pair. The resulting alliances were white with black and red, blue with red and green, black with green and white, red with white and blue, and green with blue and black. Soon after the alliances formed, they moved to their own sector of the plane.
Several millennia after the allies gathered, an enemy pair associated itself with an allied pair. The resulting alliances were white with black and red, blue with red and green, black with green and white, red with white and blue, and green with blue and black. Soon after the alliances formed, they moved to their own sector of the plane.
URG: Margof Craglands; Irmog (Kobold); Goblin and Kobold; Unknown
BGW: Yggdrasil; Winry (Elf); Elf; Unknown
RWU: Unknown; Zelda (Kithkin); Kithkin; Unknown
GUB: Unknown; Llodra (Faerie); Unknown; Unknown