A cube designed around growth. It contains no creatures except for a few Eldrazi, and instead has many cards that produce repeated value. There are thus many tokens. Most decks should be 3-color, but 2-color and 4/5-color are possible. Every color except Green has sweepers,

Primary/5c themes:
Tokens
Planeswalkers
Equipment (with runes and token-making equipment)

Medium themes:
W(bg) enchantments
Ug(brw) proliferate
B(u) Zombies
RU instant/sorcery synergies
GW(ub) +1/+1 counters
G Ramp
WG Populate+Big Tokens

mini-themes:
rb artifacts
Ru flashback
R mini-storm (via rebound)
W(b) Angels
Wb lifegain
R Chandras
(wu) Splice onto Instant/Sorcery
(rw) equipment