Cool Card Design of the Day
Way back when (circa GDS2) I explored the idea of new types of mana. It started with snow mana, flitted briefly through sacred mana, and ended badly at bird mana, lizard mana, beast mana, etc. It seemed like a dead-end.
Earlier this year, it occurred to me that the mistake wasn't caring about what produced the mana, but caring too specifically. First, the thing can't be parasitic, like snow or sacred were; it's got to be something Magic has a lot of. Second, it can't be so preposterously narrow as to carry about a specific sub-type. The reason being that we want to actually use our mechanic, and since we're inherently limiting ourselves to a set of mana producers much smaller than Any Land, we've got to keep the aperture open as wide as possible.
Magic has one card that's a model for this: