Rainbow shoots 6 shots colored in fashion similar to a rainbow. The shots are shot at the same power, but are stacked on top of each other, giving it that arcing rainbow appearance in most shots. The shots goes through terrain, making it an excellent weapon to finish off weakened foes. Damage is distance based.
If Rainbow wasn't big enough, MegaRainbow should be. With increased damage and size, MegaRainbows can hit harder and has a slightly easier time hitting.