You’re not allowed to overpay for a spell just because you want to. You can’t just choose to pay 5 mana to cast something like Radiant Flames, because its mana cost is 2R. But what we can do is have cards that increase the cost of the spell (like Vryn Wingmare or Thalia, Guardian of Thraben) to force us to pay more. And since the cost is increased, we can increase the number of different colors of mana we used to cast the spell and get a bigger effect. While we can’t naturally cast Radiant Flames with five different colors of mana, if we have two Vryn Wingmares on the battlefield, the cost of the Flames will jump to 4R. That’s five mana, and if we use five different colors of mana, we can get a Radiant Flames that deals 5 damage to everything.
Note there is a limit here: there’s only five colors in Magic. Therefore, it’s not worth boosting past 5 mana like this, since you won’t get any more bonuses once you’ve used all five colors of mana to cast the spell (Wastes don’t help, since that’s colorless mana, but we’ll get into that in more detail next week). Something like Exert Influence won’t benefit from having its cost increased, since it already costs five mana to cast anyways.
Well, that’s another exciting week here at the Rules Tip Blog. Be sure to check back next week, when we start going over some of the mechanics that will be featured in Oath of the Gatewatch. See you then!