rainbow domain

in many worlds and cultures the rainbow is a symbol of hope and unity as well as life,creation and variety though myths vary on what rainbows are they all seem to think that they an importent part of the world. rainbow god´s include the greek god iris (who also has the peace, twiglight and arcana domains) as well as  norse bifrost (not really a god though can assciated with the peace,order and light domains) many real life dragon gods are associated with rainbows as well.

expanded spell list

cleric level spells

1st    chromatic orb,color spray

3rd     dragon´s breath,blur

5th    Hypnotic pattern,beacon of hope

7th   dimension door,aura of life

9th   wall of light,teleportation

Bonus Proficiencies

When you choose this domain at 1st level,you gain proficiency with the performance skill and one other skill of your choice.

channel divinity:rainbow hope

Starting at 2nd level, you can use your Channel Divinity to vary the parties skill and keep them hopeful. As an action Choose a creature within 30 ft of you they can choose to lose a number of skill proficiencies up to your wisdom mod (at least 1) and gain a number of skill proficiencies  in skills of their choice this affect lasts or 1 hour after which their skills return to normal.

radiant hope

Starting at 6th level, your mastery of hope and the rainbow gives you the power to protect from mental dangers.

.you are resistant to psychic damage and have advantage on wisdom saves 

.you can cast calm emotions  or heroism a number of times per day equal to your  proficiency bonus.

divine strike

At 8th level, you gain the ability to infuse your weapon strikes with the radiant light of the rainbow. Once on each of your turns when you hit a creature with a weapon attack, you can cause the attack to deal an extra 1d8 radiant damage to the target. When you reach 14th level, the extra damage increases to 2d8.

rainbow mastery

At 17th level you can cast prismatic wall and prismatic spray once per day each.