Only cards printed at uncommon rarity (including MTGO-exlusive sets).
One of my favorite parts of drafting is leveraging/discovering neat little synergies between cards that might not usually be seen
together. If there's an overall design philosophy to this cube, it would be maximizing opportunities for cool, fun synergies, and
encouraging interactive gameplay. Aggro, Midrange, and Control should all be supported across multiple colors.
I want archetypes to be fairly fluid, and decks to be able/encouraged to draw from a number of synergies across colors/archetypes.
As such, fixing should support 3+ colored decks, at the cost of speed.

Individual Color Themes:W - Weenies, Tokens, O-Ring-Type Removal, Creature Protection, Dudes that Buff other DudesU - Tempo,
Flash, Fliers, Card Draw, Control, Spell SynergyB - Graveyard Recursion/Reanimation, Efficient Creature Removal, Sac Effects,
GY-Matters/Recursion, DiscardR - Sligh-Type Aggro Creatures, Spell Synergy, Burn, Sweeper Effects, TokensG - Efficient Stompy
Creatures, Ramp, Big Bois, Flash, GY-Matters/Recursion, Tokens

Intended Archetypes:
WU - Blink; Fliers (B)WB - Lifegain; Grindy Tokens (G)
WR - Go-wide/Aggro Tokens (Temp Buff Effects)
WG - Big Tokens (Permanent Buff Effects)
UB - Control/Midrange; Reanimator
UR - Control/Midrange; Prowess AggroUG - Flash Tempo; +1/+1 Counters/Proliferate
BR - Disruptive Aggro (discard); Destroy-all-monsters control
BG - GY-Matters/Aristocrats Midrange; Reanimator (lacks good ways to to get big dudes in yard, more value-reanimation)GR -
Balls-in aggro; Burny Ramp
Mono-colored aggro (probably with splash) is supposed to be viable in G, R, W, and to a lesser extent, B. This may be too many
colors to support aggro in.
I'm aware of a few infinite combos, the best probably being persist combos (Kitchen Finks/Murderous Redcap+Rhythm of the Wild/JO
Ranger/Grumgully/Zameck Guildmage+Sac Outlet). This (I hope) is somewhat controlled by pieces being vulnerable to removal, and the
lack of free sac effects outside of black (only Ashnod's Altar). Will need to do more testing to see if this is a problem.

Other infinite combos I know of:
Peregrine Drake + Scholar of the Ages/E Wit + Illusionist's Stratagem (Inf Mana)Spitemare+A way to give Mare lifelink+Valorous
Stance+Any source of damage (Inf Life)Wispweaver+Clone+An ETB Payoff (Goldnight Commander, Soulherder, JO Ranger)