The core conceit of this cube is that it's bound by two ironclad rules:

1. It must contain every planeswalker card ever printed, and

2. For every planeswalker card, there are exactly two other cards, thus keeping the ratio of planeswalkers to a consistent 1/3 of the cube.

The non-planeswalker cards are selected to support a planeswalker-heavy environment, and to encourage using planeswalkers as the meat of most decks. Therefore, I've tried to keep the number of non-planeswalker "bombs" to a minimum, and I've tried to give every planeswalker a little bit of love so that none of them are strictly unplayable. A few of the cards may be customized. For example, when you draft Nissa Revane, you automatically get 4 Nissa's Chosen added to your card pool.