The idea of this cube is to have a highly interactive environment that revolves around cheap threats that take over the game if left unchecked.
Common effects include:
Cheap creatures that grow or otherwise produce value over time
Efficient removal/countermagic
Cheap combat tricks to keep your threats around and close out games
Goals:
Tight and interactive gameplay
Short games with no board stalls
High average storm count
two-color decks that may splash for more removal, protection, or threats
Exclusions:
Planeswalkers: these lead to non-interactive gameplay and board stalls
Wraths: I want to force players to interact with early threats and not just wait until they can wipe the board.
Combo and other alternate wincons: Even though something like twin fits the description, I want value to be accumulated over time by making favorable trades and protecting your threats
Hexproof/Protection creatures: Other than a few exceptions, these go against the interactive nature of the cube.
Rigid archetypes: I think the overall goal of this cube is specific enough to not need archetypal restrictions, and I want to encourage players to dip into other colors for effects they need.
Hand reveal: I want information to be hidden to force you to play around what opponents may have