Infuse With Rainbows

As long as you control a permanent that's all five colors Infuse With Rainbows costs {0} to cast.
Destroy all mono-colored permanents. They can't be regenerated.
Put a +1/+1 counter on all creatures at the beginning of the next end step.
Iris is a wrathful and powerful being, creating and destroying as she sees fit with just a flick of her hair.