If something instructs you to add ‘one mana of any color’ to your mana pool, you have exactly five options: the five colors of magic. You can pick White, Blue, Black, Red, or Green, and you must name a color when you add ‘one mana of any color’ to your mana pool. You cannot add a ‘mana of not-yet-chosen color’, and have it function as whatever color you want later on, nor can you pick colorless. If you plan to float mana, you’ve got to make it known what mana you will have floating.

A judge probably won’t blink twice if you tap 4 Reflecting Pools, a Vivid Grove, and a Forest to cast Primeval Titan without declaring what color the Pools were tapped for, but if you tap them to float 4 mana you aren’t going to use immediately, you’ll have to choose colors right then and there.

Today’s Rules Tip written by
Trevor Nuñez, Level 1 judge from Roswell, NM