Reaper King

A card with monocolored hybrid mana symbols in its mana cost has a mana value equal to the highest possible cost it could be cast for. Its mana value never changes. Thus, Reaper King has a mana value of 10, even if you spend white mana blue mana black mana red mana green mana to cast it.

If a cost includes more than one monocolored hybrid mana symbol, you can choose a different way to pay for each symbol. For example, you can pay for Reaper King by spending one mana of each color, 2 generic mana and one mana each of four different colors, 4 generic mana and one mana each of three different colors, 6 generic mana and one mana each of two different colors, 8 generic mana and one mana of any color, or 10 generic mana .

If an effect reduces the cost to cast a spell by an amount of generic mana, it applies to a monocolored hybrid spell only if you've chosen a method of paying for it that includes generic mana.