Momir Basic is originally a format available on Magic Online, where each player competes with a deck of sixty basic lands and a Momir Vig, Simic Visionary avatar with the following rules text.
The objective of the game is to win the game using creatures created by Momir's ability. This cube is an attempt to duplicate this format as best as possible in paper Magic.
The cube is a collection of cards containing many creatures (though not all) from the history of Magic, sorted in piles by its converted mana cost. When a player activates Momir's ability for a certain value of X, a card from the appropriate pile is selected and random and put into play.
Since it is unfeasible to have the cube actually contain every single creature card in the history of Magic, the aim of the cube is to select a small, but representative sample of all the creatures in Magic. The objective of this cube is to make it an unbiased subset of all Magic cards such that some basic strategy applicable in the true Momir Basic format on Magic Online are still generally useful for playing this cube.
In its current state, the cube is not completed. In fact, this is a project that will probably never be truly completed: cards will constantly be added and removed to try to achieve a delicate balance.