Void Domain

Clerics draw their power from the God of the Domain they choose. Void Clerics are the exception.

There is a world between the worlds, bereft of color, emotion, sound, and every other conceivable thing that is the stuff of reality. The Voids whispers are subtle, and it draws those in who seek absolute peace, stillness and serenity. But it is also a source of great power if one is willing to invite madness and disturb the normally so serene and calm currents of the void.

Power Word: Void

Beginning at 1 Level when choosing this domain, as a Bonus Action the Cleric can cause a creature within 30 feet to suffer Psychic Damage equal to twice their Proficiency Modifier, as the targets mind is assaulted by Eldritch Knowledge and whispers. This can be used a number of times per Long Rest equal to the Clerics Wisdom Modifier. Alternatively, if the Cleric uses their Channel Divinity or a Spell Slot of 1 Level or higher to cast an Illusion Spell, they regain one use of this feature.

Additionally, the Cleric knows the Mind Blast Cantrip and it doesn’t count against their maximum number of Cantrips known.

Mind Blast:
Level: Cantrip
Casting Time: 1 Action
Range/Area: 15ft. cone
Components: V,S
Duration: Instantaneous
School: Illusion
Attack/Save: CHA Save
Damage/Effect: Psychic

The Caster reaches forth his hand and a wave of lethargy washes over creatures in a 15 ft. cone. Creatures in that cone must make a Charisma Saving Throw or suffer 1d6 psychic damage. This damage increases when the character reaches certain levels. 2d6 (5th level), 3d6 (11th level) and 4d6 (17th level)

Channel Divinity: Void Shape

Beginning at 2nd Level, as an action, the Cleric temporarily becomes a reincarnation of themselves in the form of the Void, a hole in reality in the shape of the cleric, filled with a sky covered in blinking eyes and writhing madness.
For 1 minute, whenever the Cleric causes a creature to suffer Psychic Damage, that creature suffers an additional amount of Psychic Damage equal to the Clerics Wisdom Modifier. When he uses Power Word: Void while in Void Shape, the creature suffers three times the Clerics Proficiency Modifier in Psychic Damage instead of twice.

Channel Divinity: Infinite Stars

Starting at 6 level, as an action, the Cleric causes the sky itself to bulge down to the world. A meteor of void and starlight envelopes a point within 60 feet of the Cleric with a Radius of 20 feet. Creatures within that sphere have to make a Charisma Saving Throw. On a fail, they are incapacitated until the start of the Clerics next turn.

Strength from Madness

Starting at 8 Level, once per Long Rest, if a creature within 60 feet of the Cleric suffers Psychic damage, the Cleric may use his reaction to gain temporary hit points equal to the amount of psychic damage suffered by the creature. If the Cleric uses their Channel Divinity or uses an Action to expend a Spell Slot of 1 Level or higher, they regain one use of this feature.

Additionally, if the Cleric concentrates on a Spell and suffers damage, he does not have to make a Concentration check as long as he has temporary hit points left after the attack dealt its damage.

Lurking from Beyond

Starting at 17 Level, the Cleric becomes immune to madness effects since he is already steeped so deeply in Insanity, it would be inconceivable to distinguish the different kinds of mental derangement he would be afflicted by. Additionally, during combat, the void reaches out in tendrils from the Cleric. At the end of his turn, every enemy creature within 10 feet of him suffers 10 points of Psychic Damage. The Radius then increases by 10 feet, to a maximum of 30 feet. This effect ends and resets as soon as combat ends.