Cosmic Domain

The stars above, the nebulae which birth them, the vacuum of the cosmos, the galaxies that scream through the void, and all the innumerable things to find in the universe are, themselves, powers. A Cosmic Domain Cleric is one who embodies an infinitesimal but potent fraction of the universe, able to exhume radiant light as a star and to create void like the space between everything. You are the face of the universe in all its omnipresence.

Void Sight

You have 60 feet of darkvision if you do not already have it. If you do, your darkvision range increases by 60 feet.

Additionally, you can see in magical darkness with your darkvision as if it were normal darkness.

Solar Flare

Also at 1st level, when you deal damage with a spell that deals cold, fire, or radiant damage, you deal extra radiant damage equal to 2 + the spell's level (minimum of 2 radiant damage).

You also know the fire bolt spell. It is a cleric spell for you and does not count against the number of cantrips you can have prepared.

For the Cosmos

You have resistance to cold, fire, and radiant damage from spells you cast and from astronomical phenomena (such as the heat of a star or intergalactic space.)

You are also able to breathe while in a vacuum (such as the vacuum of space or the interior of a bag of holding.)

Channel Divinity: Avatar Faculae

Starting at 2nd level, you can use your Channel Divinity to empower yourself with solar fire, creating heat that only the mightiest stars can produce. 

As an bonus action, you present your holy symbol. For 1 minute, when a creature takes radiant damage from a spell of 1st level or higher that you cast, that creature and each creature of your choice within 5 feet of that creature must make a Constitution Saving Throw. On a failed save, a creature takes radiant damage equal to half your cleric level rounded up and is blinded until the end of that creature's next turn. On a successful save, the creature takes no damage and is not blinded.

Additionally when you activate this ability and as bonus action on subsequent turns until the ability ends, spells you cast your turn that deal fire damage instead deal radiant damage.

Channel Divinity: Entropic Wave

As an action, you can use your Channel Divinity and present your holy symbol to release a wave of energy sapping void. You create a void of darkness in a 60 foot radius centered on you which also extinguishes all light sources which become enveloped within the darkness. This darkness moves with you, spreads around corners, and is considered magical darkness and can't be dispelled with magical light. This darkness lasts until the start of your next turn.

Additionally, each creature of your choice that you can see or hear within 60 feet of you gain the benefits of your Void Sight ability until the darkness start of your next turn. Creatures other than those you chose cannot regain hit points while in the darkness.

Nova Flare

Starting at 8th level, you add your Wisdom modifier to the damage you deal with any cleric spell that deals cold, fire, or radiant damage.

The Great Attractor

Starting at 17th level, you can assume an astronomical form of an extension of the will of the cosmos. As an action, you can assume this form for 1 minute which you can end early as an action. While in this form, you gain the following benefits:

• When you cast a spell that deals cold, fire, or radiant damage, your spell save DC and spell attack bonus both increase by 2 for the duration of that spell for that spell only.
• You have immunity to cold, fire, and radiant damage.
• While using the Avatar Faculae ability, creatures who fail the saving throw instead take damage equal to your cleric level and creatures who succeed instead take damage equal to half your cleric level.
• You have a flying speed of 15 feet and can hover.

Once you assume this form, you can’t do so again until you finish a long rest, unless you expend a spell slot of 8th level or higher to use this feature again.