> > In the Pokémon trading card game, energy that satisfies a > > basic energy requirement but doesn't have an element (fire, > > water, psychic...) associated with it is called "Colorless Energy". > > Maybe we can do the same with the pyramids, since the > > "Colorless Pyramids" don't have any colors of their own. > > That's actually quite different. That mechanic is used to denote that > the requirement is color blind. A Clear (or Transparent or > Achromatic) pyramid has the property of having no color. > > Your colorless energy (or mana, or what have you) refers to all > colors. A colorless pyramid refers to a particular subset. Actually, that's not the case, entirely. The colorless energy symbol, when used in a cost, denotes a generic cost, as you say. However, there are colorless energy cards that actually *produce* colorless energy. It is exactly an analog of the Magic: the Gathering mana system, where you have generic mana costs that can be paid with any type of mana (well, unrestricted mana, at least, for you other rules lawyers) and you can have colorless mana in your mana pool. The same symbol is used to indicate both connotations.