Circle of the Rainbow

Hue Maker

Starting at 2nd level, you gain the light cantrip, and it counts as a druid spell for you. When you cast light, you can have the light it creates shine with a multitude of different colours of your choice. 

Nature's Prism

At 2nd level, you learn to unleash your druidic magics in the form of a prismatic arc of light. As an action, you can manifest a rainbow originating from a point within 30 feet of you, in the form of a line of bright light 5 feet wide and 30 feet long. The rainbow remains for 1 minute, until you dismiss it as a bonus action, or until you are incapacitated. The rainbow radiates dim light within 5 feet, suppresses magical darkness within it, and creatures of your choice within it only need to use 1 feet of movement for every 2 feet they travel.   Additionally, when you cast a Druid spell of 1st level or higher, the rainbow momentarily pulses with protective light. Creatures of your choice within the rainbow immediately gain an amount of temporary hit points equal to half your druid level. These temporary hit points fade after 1 minute.   Once you have used this feature, you can't use it again until you complete a short or long rest.

Chromatic Discharge

At 6th level, while you are in an area of bright light, you can use your action to release a multicoloured beam at a nearby foe. Make a ranged spell attack against a creature within 30 feet of you. On a hit, the creature takes radiant damage equal to your Wisdom modifier and must succeed on a Constitution saving throw or be blinded until the end of its next turn. A creature that takes any of this damage glows with a rainbow hue, shedding bright light within 5 feet, and dim light for 5 feet beyond that.   Once you have used this feature, you can't use it again until you complete a short or long rest.

Double Rainbow

Beginning at 10th level, when you create your rainbow, you can have it become either 10 feet wide, or 60 feet long, your choice.

Herald of Hues

  At 14th level, you can expend two uses of Wild Shape at the same time to summon the herald of rainbows, an alicorn. A winged unicorn with an irridescent mane, the alicorn uses the statistics of a pony (see the Monster Manual or appendix C of the Player's Handbook), with the following changes:

• It is a celestial.
• It has an AC of 15, additional hit points equal to twice your druid level, and a flying speed equal to its walking speed. 
• It has advantage on saving throws against spells and magical effects. 
• It can attack with its horn, with a +4 bonus to hit and dealing 1d10 + its Strength modifier in magical piercing damage.

The alicorn appears in an unoccupied space of your choice within 30 feet of you, and obeys any verbal command you issue to it (no action required by you). If you don't issue any commands, it stays within 5 feet of you and defends you from hostile creatures. In combat, the alicorn rolls its own initiative and acts on its own turn. It vanishes after 1 hour, or when it is reduced to 0 hit points or dies.   Additionally, the alicorn can be used as a mount by any friendly creature of Medium size or smaller, and while it is within the rainbow created by your Nature's Prism feature it is immune to all damage.