A graveyard cube, where all colors and color-combinations are using the graveyard as a resource.
The cube aims to be cheap enough to own, and hopefully hits just the right spot of complexity. Each color combination is ideally the following archetype:
WU - Control/Tempo
UB - Enemy Graveyard
BR - Discard
RG - Monsters/Stompy
GW - Go Wide
WB - Reanimation
UR - Spells Matter
BG - Dredge
RW - Self GY "Exiling"
GU - Delirium/GY Accumulation
Some of them are still in progress or in some sense of identity crisis, mostly Simic and Gruul, but they generally have some thought added to them.