The following homebrew adds a mythic option to the Barbarian class in 5E TTRPGs. All of the core Barbarian class abilities can stay rules as written; see the official 5E System Reference Document (SRD v5) for details. Note: This subclass has not yet gone through playtesting.
Demigod
The blood of ancient gods burns within you, not as serene grace but as volcanic fury. Your ancestors wove the fabric of creation in way far beyond mortal understanding. Demigod barbarians are born of Olympians, Aesir, Vanir, Anunnaki, or other divine lineages that channel divine power through emotion rather than faith. Their rages become radiant storms, their blows crackle with the thunder of the heavens, and in moments of need, their fury ignites into true miracles known as Wondrous Deeds.
Demigod Lineage Examples
* Zeus / Thor / Indra: Lightning flickers through your hair; thunder follows your blows.
* Ares / Tyr / Ninurta: Your veins glow red with divine fury; your strikes quake the ground.
* Athena / Frigg / Enki: Your eyes gleam with golden strategy; enemies falter before your calm wrath.
* Poseidon / Njord / Enlil: Waves and storms answer your rage; water churns beneath your steps.
* Hades / Hel / Ereshkigal: Shadows bend toward you, and your fury chills the air.
* Aphrodite / Freyja / Ishtar: Your beauty terrifies and exalts; each strike is both mercy and judgment.
Level 3: Divine Heritage
Your lineage reveals itself when you rage: Wings of flame, lightning in your eyes, or a divine symbol burning on your brow.
* Divine Damage. When you rage, you may choose for your bonus damage to be radiant, lightning, or thunder instead of the usual bludgeoning/piercing/slashing bonus.
* Celestial Tongue. You can speak, read, and write Celestial (or another divine language appropriate to your ancestry).
* Deific Presence. You gain proficiency in Religion or Persuasion (your choice).
Level 3: Wondrous Deeds
Your rage can manifest as acts of divine power. You can expend your uses of Rage to perform miracles rather than enter a rage.
Spellcasting
You gain limited spellcasting fueled by divine fury:
* You can cast spells using Charisma as your spellcasting ability.
* You know two spells of 1st level from the Cleric or Paladin spell list (your choice).
* When you gain levels in this class, you can replace a known spell with another from those lists.
* You gain additional known spells at higher levels (see table below).
Barbarian Level … Spell Level, # Spells Known
* 3rd Level … 1st level spell, 2 spells known
* 6th Level … 2nd level spell, 3 spells known
* 10th Level … 3rd level spell, 4 spells known
* 14th Level … 4th level spell, 5 spells known
Divine Slots
You do not gain spell slots normally. Instead, you can expend a Rage use to create a temporary spell slot:
Rages Spend … Spell Slot Level
* 1 … 1st level spell slot
* 2 … 2nd level spell slot
* 3 … 3rd level spell slot
* 4 … 4th level spell slot
You may only have one such slot active at a time, and it lasts for 10 minutes or until expended. You regain all expended Rages when you finish a long rest. Example: A 6th-level Demigod Barbarian with 3 rages could instead perform three 1st-level Wondrous Deeds, or combine them for one 2nd-level and one 1st-level Deed.
Casting While Furious
You can cast spells even while raging as your magic is physical, not cerebral. While raging, your concentration checks for maintaining spells gain advantage, and you may use Strength instead of Charisma for spell attack rolls and saving throw DCs (choose each time you rage).
Level 6: Divine Resilience
Your godly vitality awakens fully.
* You gain resistance to radiant damage, and advantage on saving throws against being charmed or frightened.
* When you take damage that would reduce you below half your hit point maximum, you may cast Cure Wounds on yourself as a bonus action using a Wondrous Deed slot if available.
Level 10: Avatar’s Aura
Your divine essence radiates like a beacon. While raging or performing a Wondrous Deed:
* Allies within 10 feet gain +1 to AC and advantage on saving throws against fear.
* When you cast a spell of 1st level or higher, you can emit a radiant shockwave dealing your Charisma modifier in radiant or thunder damage to enemies within 10 feet.
Level 14: Celestial Ascendant
You have nearly achieved apotheosis.
When you enter a rage, spectral wings, halos, or divine marks flare around you; you gain a fly speed of 30 feet while raging.
You can now convert two Rages at once to create a single 5th-level Wondrous Deed slot.
Once per long rest, when you drop to 0 hit points, you can instead drop to 1 hit point and immediately cast any spell of 4th level or lower you know without using a slot as a last, desperate miracle.