This is a concept cube: I picked one planeswalker for each 2-color combo, and structured each 2-color draft archetype around that planeswalker's abilities. The colors are evenly balanced, and there is a decent amount of bleed-over within each color so that every card can play a role within a deck of that color, even if it is not the specified archetype. That said, the archetypes are as follows:

W/U (Venser) - Flicker
U/B (Tezzeret) - Affinity
B/R (Daretti) - Sacrifice
R/G (Xenagos) - Ramp/Monstros
G/W (Ajani) - +1/+1 Counters
W/B (Sorin) - Lifegain
B/G (Vraska) - Delirium
G/U (Kiora) - Cascade Scry
U/R (Dack) - Flashback
R/W (Nahiri/Huatli - change in process) - Cheating Creatures