Way of the Heavenly Demon

Through one way or another, you have found yourself as an inheritor of a Heavenly Demon's techniques. A Heavenly Demon is one who strays from the true path of cultivation in pursuit of their own desires, regardless of the consequences to themselves and those around them. Learners of such foul arts are often referred to as heretics, or demonic cultivators. These practitioners of dark martial arts are often exiles, taking orders from no one except their own ambitions.

Weapon Cultivation

Starting at 3rd level, you select a weapon that you deem worthy to accompany you on this solitary path. You gain the following benefits.

• You gain proficiency in one martial weapon of your choice. This weapon counts as a monk weapon for you.
• You can ignore the strength requirements of weapons you are proficient in with the heavy property.
• You can replace your Bonus Unarmed Strike with an attack made with this weapon.

Demon Arts

Starting at 3rd level, your connection to the spirit realm allows you to perform Demon Arts in combat in exchange for your own life force. Demon Arts are devastating techniques gifted to you by the souls of the departed, allowing you to surpass your mortal limits. You can expend your hit die to fuel your Demon Arts. You learn two Demon Arts when you select this subclass, and learn 1 more at levels 7, 11, and 15. When you learn a new Demon Art, you can replace one you know with another from the list. You can only use your Demon Arts when you have a melee weapon that you are proficient with equipped.

Your Demon Art Save = (8 + Proficiency bonus + your Wisdom modifier) 

Gale (1 hit die): When you make an attack, you can expend 1 hit die and replace the attack to swing your weapon, sending a shockwave outward in a 20ft cone originating from you. Each creature within the cone must succeed on a Dexterity saving throw or take damage as though you had hit them with an attack from your weapon. 

Hurricane (1 hit die): When you make an attack, you can expend 1 hit die and replace the attack to swing your weapon around you at incredible speed. Each creature within 10 feet of you must succeed on a Dexterity saving throw or take damage as though you had hit them with an attack from your weapon. 

Karmic Strike (1 hit die): When a creature makes an attack against you or an ally within 5 ft, you can expend 1 hit die and use your reaction to make an attack of opportunity against the creature. 

Sword Pressure (1 hit die): The pressure from your techniques strikes fear in the hearts of even the most audacious foes. When you hit a creature with an attack, you can expend 1 hit die and have the target make a Wisdom saving throw and become frightened of you for one minute on a failure. The frightened target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Flurry of Steel (1 hit die): You can expend 1 hit die instead of 1 focus point to use Furry of Blows and replace any number of unarmed strikes made with melee Monk Weapon attacks.

Whirlwind (2 hit die): As a bonus action, you can expend 2 hit die and teleport a number of feet equal to your walking speed to an unoccupied place you can see. 

Courting Death (2 hit die): As a reaction, you can expend 2 hit die and assail a creature that attacked you this round with the full might of your ki. The target must succeed on a Wisdom saving throw or become paralyzed until the end of your next turn. 

Drink (2 hit die): When you hit a creature with an attack, you can expend 2 hit die and siphon their life from them. You regain the damage dealt in the attack as hit points. 

Swallow Counter (3 hit die): As an action, you can expend 3 hit die and unleash a series of lightning fast strikes that attack everything in a 30ft emanation originating from you. Each creature within the radius must succeed on a Dexterity saving throw or take damage as though you had hit them with an attack from your weapon. On a successful save, a creature receives half damage. You may use this Demon Art once per short or long rest.

God Eater (3 hit die): As a bonus action, you can expend 3 hit die and imbue your weapon with foul ki. Until the end of your next turn, when you hit a creature with an attack, they take additional thunder damage equal to damage dealt. You may use this Demon Art once per short or long rest.

Forbidden Technique

At 6th level, your understanding of ki has allowed you to siphon it from your slain foes, rejuvenating you. Whenever a creature dies within 10 feet of you, your lifespan is increased by a year, and you gain one of the following benefits.

• You gain a temporary hit die.
• You gain a temporary focus point.

You cannot have more hit die or focus points than your maximum totals for each as a result of this feature. You lose the hit die or focus points granted by this feature by the end of your next turn if you have not spent them.

Master of the Arts

At 11th level, your innate understanding of your Demon Arts has allowed you to use them in their truest form. Your Demon Arts improve in the following ways:

Gale: A creature receives half damage on a successful save. 

Hurricane: A creature receives half damage on a successful save. 

Karmic Strike: You may make the attack of opportunity at advantage. 

Sword Pressure: A creature's movement is halved on a successful save. 

Flurry of Steel: You make these attacks at advantage.

Whirlwind: After teleporting, you can make a single attack with your equipped weapon against a creature within range. 

Courting Death: The creature's movement is halved on a successful save. 

Drink: The attacked creature can't gain life until the end of their next turn. 

Swallow Counter: Each creature takes additional thunder damage equal to your monk level on a failed save, and half damage on a success. 

God Eater: Every time you hit a creature with an attack until the end of your next turn, you regain 1 hit die.

Heavenly Demon Asura

At 17th level, your training has enabled you to be able to fully integrate the Heavenly Demon's techniques are your own martial arts, proving you worthy to inherit the title of the Heavenly Demon Asura itself. You gain the following benefits:

• You may use your hit die instead of focus points for your monk class features.
• You may use your focus points instead of your hit die for your Demon Arts.
• You may choose both options from Forbidden Technique, and they no longer go away if unspent.