Color Balance

The most important aspect of balance is to have the same number of cards per color. Here's a good starting point for your 360-card cube:

60 white cards
60 blue cards
60 black cards
60 red cards
60 green cards
30 nonbasic lands
30 colorless artifacts
Here's another template, this time with multicolored cards included.

50 white cards
50 blue cards
50 black cards
50 red cards
50 green cards
50 multicolored cards, with five of each color pair
30 nonbasic lands
30 colorless artifacts
Artifacts are tricky because some of them either have a colored activation cost or reference a certain color. For example, Vedalken Shackles should be counted as a blue card and Shrine of Burning Rage as a red card. Don't count artifacts as colorless artifacts if they are only for one specific color.


Etched Champion | Art by Matt Cavotta
Nonbasic lands are great at helping you get the right colors you need for your deck, but they should be chosen with care. I recommend playing three ten-card cycles, with a land for each color pair. For example, you could play the ten Shadowmoor filter lands, the Ravnica shock lands, and the ten fetch lands. What I'd stay away from are cycles that only provide you with five lands, like the Battle for Zendikar battle lands. Since these lands only provide you with ally color mana fixing, players will be encouraged to draft ally color pairs over enemy ones.

Archetypes

Selecting cards for a 360-card cube is not an easy task, and you may have no idea where to begin. A good starting point is to choose your favorite archetype for each of the ten color pairs and include cards that support those archetypes. Still lost? Here is an example of some popular Cube archetypes for each color pair.

White-blue—Control
Blue-black—Reanimator
Black-red—Sacrifice
Red-green—Ramp/Stompy
Green-white—Counters/Proliferate
White-black—Life Gain
Black-green—Graveyard Shenanigans
Green-blue—Creatures/Card Advantage/Ramp
Blue-red—Spells/Combo
Red-white—Aggro/Burn