After watching everyone's games, debriefing the players and considering the various match-ups, I've come to the following changes:

-Rakdos gets louder signpost gold cards for its sac theme as well as a power injection enabler in Goblin Bombardment.

-Arc Trail comes in as a check vs tokens and aggro strats. Similarly, this is the argument for Archfiend of Sorrows (also adds a great reanimator payoff for UB.)

-Gruul gets an actual ramp payoff in Phylath which both stabilizes and then wins over the course of a couple turns if you untap with it.

-A couple of optimization changes in mana and cards with better efficiency/casting costs.

-Trims were cards that didn't have a purpose anymore. Previously I wanted generically playable cards in the cube for players that had trouble making playables/finding a lane. These would be players inexperienced in limited (cube in particular.)

My current philosophy on the design of this cube is that cards need to fill one of three roles:

1. Powerful card that pulls you into a color.
2. Card that pulls you into an archetype (enabler or payoff.)
3. Card that straddles two lanes (archetype overlapping cards.)

Future considerations for cuts:
Shivan Wurm
Magus of the Scroll

Future Maybes:

White:
Clarion Spirit
Luminarch Aspirant
Teleportation Circle

Blue:
Behold the Multiverse

Black:
Elderfang Disciple
Sedgemoor Witch
Ebondeath, Dracolich
Power Word Kill

Red:
Plargg, Dean of Chaos
Magic Missle

Green:
Esika's Chariot
Sarulf's Packmate

Gold:
Vanishing Verse