beast of rainbows

You summon a multi-colored beast that you can command telepathically as a bonus action. If you don't tell it to do anything it will protect you from hostile creatures. You can make it take on any form that has a challenge rating of 5 or lower, but no matter what form it takes on it is still colored like a rainbow. It can use any action its form can ussually take with a few acceptions. ONE. Any fire, ice, lightning, or any other energy it produces is rainbow colored. AND TWO. It can take one extra action that it can only use once per every natural rainbow that it sees while under your comand, this action allows it to use any spell at level 6 or lower without expending a spell slot and without any material components. You can use your action to dominate the creature and control it. You take on all of its traits but keep your alingment, intellingence, and charisma scores.