Image imported from derpibooru
Original Description:

Rainbow of Darkness corrupt and change Shining Armor into monster.

Rainbow of Darkness: Ah, Shining Armor the former captain of guards and king of Crystal Empire. I can see you feel useless because you fall protect to loven ones and being defeated by villains. And I can see your jealousy for sister Twilight Sparkle chuckle, don’t hide I know you feel jealous when you witness that sister become succefull when each defeat villains when you gain more failure. I can understant you feeling being shadow of sibling. In past I and my sister have duty to balance universe. I bring darkness when is to much light and punish guilty, when my sister bring light when is to much darkness and give hope to lost one. But when time passed the creatures loved and adore my sister benevolence while I only get scorn and hate! I was tired this! They wanted a monster so they got a monster! And Shining Armor I grant a power that you will defeat enemies, no more failure and no more being sister’s shadow. Now you are not weak Shining Armor anymore, now you are Fright Knight the ferocious warrior that will destroy enemies in sight.