Madness Domain
Gods whose portfolios include the Madness domain - such as The Fury, Thoon, and Ralishaz - govern over the vagaries of insanity in its myriad aspects. They send forth their Clerics to proselytize the freedom from linear thought and the insight of madness. As such, most Clerics that carry this domain are Evil, though there are exceptions.
Madness Domain Spells
1st - Dissonant Whispers, Tasha's Hideous Laughter
3rd - Crown of Madness, Detect Thoughts
5th - Clairvoyance, Hypnotic Pattern
7th - Confusion, Hallucinatory Terrain
9th - Contact Other Plane, Modify Memory
Insanity's Prophet
At 1st level, you learn one bard cantrip of your choice. You also gain proficiency in one of the following skills of your choice: Deception, Insight, or Perception.
Controlled Descent
Also at 1st level, you develop a form of control over any madness you might develop - you may take Reactions while under the effects of Confusion, and you may add your Wisdom modifier to the 1d10 roll determining your behaviour each turn. In addition, whenever you fail a save against an effect that would leave you charmed, you may choose to be affected by a Confusion effect instead, which lasts for the duration of the other effect.
Channel Divinity: Splinter Tiny Minds
Starting at 2nd level, you can replace the fires and ices of this world with gibbering and screaming.
Whenever you cast a spell that deals acid, cold, fire, lightning, or thunder damage, you can use your Channel Divinity to have it deal psychic damage instead.
Madness Paramount
Starting at 6th level, psychic damage dealt by your spells ignores any resistances a creature might have.
Potent Spellcasting
At 8th level, you add your Wisdom modifier to the damage you deal with any cleric cantrip.
End of All Reason
At 17th level, you can fill your spells with the full force of your deity's madness.
Any creature that fails a save against one of your spells that deals psychic damage or which inflicts the charmed or frightened conditions has Disadvantage on all Wisdom rolls and Wisdom saving throws for the next minute.
Harlequin
Circus performers or dancers before kings, Harlequins epitomize grace and physical flow. They dance through both life and combat, with a disregard that borders on careless. But somehow... it seems to work.
Mocking Performer
When you select this archetype at 3rd level, you gain proficiency with Performance if you don't have it already, and learn the Vicious Mockery cantrip; your spellcasting ability is Charisma.
Harlequin's Dance
Also at 3rd level, you may use your bonus action from Cunning Action to rise from prone without spending movement, to ignore difficult terrain for that turn, or to take the Dodge action; if you take the Dodge action with your bonus action, you take a level of Exhaustion from the strain.
Laughing Rebuke
At 9th level, you may use your reaction to make an opportunity attack or use Vicious Mockery against creatures that miss you with a melee attack.
Knife-Flower Willow
At 13th level, if a creature who has disadvantage on their attack roll misses you, the next attack you make against them before the end of your next turn may be a Sneak Attack even if you don't have advantage on your attack roll.
Seven-Shadows Evasion
At 17th level, whenever you are forced to make a saving throw, you may use your reaction to make a Dexterity saving throw instead of using the normal ability score. Once you have used Seven-Shadows Evasion, you must make a short or long rest until you may use it again.
Ghost-Blooded (Sorcerous Origin, Ghost)
Some people are blessed by death; whether they had a narrow scrape when they were a child, their mother was possessed by a Ghost while they were in the womb, or they have died and come back, they are forever marked by their half-dead nature.
Dead Heritage
At 1st level, you gain the Undead Nature trait; you may be turned as if you were Undead, but may not be destroyed by failing your save against Turn Undead. You also learn the Chill Touch cantrip.
Walk Through Flesh
Also at 1st level, you may move through creatures as if they were difficult terrain, your body briefly becoming a chill mist that passes through flesh like a biting wind. You may also see up to 20ft, plus 20ft x the highest spell level you can cast, into the Ethereal plane while on the Material Plane, and vice-versa.
Ghostly Nature
At 6th level, you may use Walk Through Flesh to move through objects as if they were difficult terrain; ending your turn inside an object causes you to take 1d10 force damage. You also gain immunity to your choice of the charmed or frightened conditions.
Ethereal Mastery
At 14th level, you must replace one of your spells known with Etherealness if you do not already know it. You also are immune to both the charmed and frightened conditions, and may use the Possession action of a Ghost.
Horrific Visage
At 18th level, you may reveal the mark of your near (or actual) death for the world to see, a nauseating spectacle of rotten flesh and bloated viscera. As an action, you may spend 5 Sorcery points to reveal your horrifying rotten visage, horrifying those that can see you clearly. For the next minute, or until you lose your concentration, each hostile non-Undead creature that starts their turn inside 60' must succeed on a Wisdom saving throw or be frightened until the aura ends.
Any creature that fails a saving throw also ages 5 years; any creature that succeeds on their save is immune to your Horrific Visage for the next 24 hours.