Counter target spell. Clash with an opponent. If you win, at the beginning of your next main phase, you may add an amount of equal to that spell’s mana value. (Each clashing player reveals the top card of their library, then puts that card on the top or bottom. A player wins if their card had a higher mana value.)
You can't add just some of the mana. You either add all the mana or none of it.
01-10-2007
wotc
You decide whether or not to add that much {C} as the delayed triggered ability resolves at the beginning of your next main phase. You don't decide before then.
Random a card of Magic: The Gathering (MTG), but you can also roll the D20 dice, random a Planeswalker, have fun with the random rules and more.