Fast, creature-oriented gameplay. Curves are low and aggro is very much supported.
Approximate balance among colors and strategies. I've done my best, but only more playtesting will determine whether I've succeeded.
Relatively high power level (for Peasant). I have not attempted to maximize power level (whatever that would mean), since considerations of fun and balance take priority. But you'll see many of the staples of Peasant cube make an appearance here.
Flexibility as to what each color pair can do. Although some gold cards support specific mechanics (e.g. Conclave Mentor, Mayhem Devil), in general my gold cards are not intended to be "signposts" dictating the direction of a color pair. Many are just generically useful cards.
Some notable omissions from the cube:
Planeswalkers. I just never liked them.
Double-face cards. Too clunky in paper.
Excessive mechanical complexity, e.g. Mutate, Day/Night, Venture into the Dungeon.
Monarch and Initiative (e.g. Palace Jailer, Goliath Paladin. Too strong and snowbally in a single-player context (and the complexity of Initiative also runs afoul of the previous stipulation.)