text: Reflecting Pool checks the effects of all mana-producing abilities of lands you control, but it doesn't check their costs. For example, Vivid Crag says "{T}, Remove a charge counter from Vivid Crag: Add one mana of any color." If you control Vivid Crag and Reflecting Pool, you can tap Reflecting Pool for any color of mana. It doesn't matter whether Vivid Crag has a charge counter on it, and it doesn't matter whether it's untapped.