EDH cube 4-8 players
Based on wizard's commander cube, will edit more after playtesting.
20 cards packs, 2 cards per pick, 60 card decks.
Low power, high synergy.

Considering giving all mono-coloured and colorless generals "partner" to make them more appealing.
Have to make sure that the average powerlevel between generals is pretty consistent (or at least each general is unique), so that one isn't always preferred over another in most/all cases.
Also considering using some of Brandon Sanderson's commander cube ideas, particularly the crowns to add extra colour's to your deck -> this can also be achieved by giving more legends "partner".
Also considering removing the colour identity from lands, so a Jungle Shrine (naya tri-land) can be played in a Boros, Selesnya, or Gruul deck.