Text (CS): Cumulative Upkeep - Add {R} to your mana pool.
The text "Add {R} to your mana pool" is a cost. This enchantment does nothing but add increasing amounts of mana to your mana pool during your upkeep. Any of this mana that isn't spent during your beginning phase (that is, during the rest of your upkeep and your draw step) will cause mana burn. [Coldsnap FAQ 2006/06/14]
You are not forced to take the mana. You can choose not to pay the cost. [D'Angelo 2006/08/01]
