One thing I learned on this project is that, when working on Universes Beyond sets, you have to trust the "rule of cool." A lot of people were mystified by why there was one meld pair but many people we spoke with who had played FINAL FANTASY XIII thought it was perfect
Add Robin Hood Archery Contestant into that with some steel damage to start it up, and we have a theme emerging
The White, Blue, and Black (or Esper) deck for Final Fantasy is built around Y'shtola, Night's Blessed, who incentivises you to cast multiple noncreature spells with mana value 3 or greater in a single turn to drain your opponents and draw cards along the way
With a limitation of only one or two ink types in a single playable deck, players must look within each type to find the best cards for their decks
Eden, Seat of the Sanctum Having a land that does something later in the game is a useful tool to mitigate flood, so I doubt Eden, Seat of the Sanctum is utterly unplayable