Monks of the Way of the Demon are burdened with a second soul living withing them, the soul of a demon. They walk through life struggling to keep the demon's soul contained afraid it may consume them completely, should it ever be let lose. Through rigorous training and meditation they have come to be able to rely on small fractions of the demon's power and wield it along with their martial arts, and perhaps one day find a true solution to the conundrum which they face. 

Level 3: Demon's Wrath

Starting when you choose this tradition at 3rd level, you can borrow your demon's power when you harness your own. Whenever you hit a creature with an attack you can spend a focus point to roll your Martial Arts die and add the damage to your attack as force damage. This ability caps at 1d10. 

In addition, whenever you make an attack using your Unarmed Strikes or Monk weapons you can change the damage type to either Bludgeoning, Piercing, or Slashing damage.

The save DC for this subclass equals (10 + Constitution modifier + Proficiency Bonus), and any monk feature, trait or ability that uses your Wisdom modifier is replaced with your Constitution modifier. 

Level 6: Demonic Endurance

You gain the ability to call upon the power of the demonic soul living within you. As a Bonus Action you can expend 3 Focus Points to gain a number of temporary Hit Points equal to your Constitution modifier multiplied with your Monk level to a maximum of 100 Hit Points. 

This ability requires Concentration. When you take damage, you must succeed on a Constitution saving throw for each source of damage, or your concentration is broken. If your Concentration breaks, you lose your temporary Hit Points. 

You can use this feature twice, and you regain all expended uses when you finish a Long Rest. 

In additon you also gain Proffiency in Constitution saving throws. When you get Disciplined Survivor at level 14 your Proffiency in Constitution saving throws is increased to Expertise. 

Level 11: Demonic Retribution

You can expend 4 focus points and take this Reaction when you would take damage from an attack. Your Speed is halved until the end of your next turn, and you gain Resistance to Slashing, Bludgeoning, Piercing, Force, Fire, Cold, Lightning, Thunder, Poison and Acid damage until the end of the attackers turn. 

During your next turn you can use your Action to teleport next to the enemy who attacked you during Demonic Retribution. The enemy then makes a Constitution saving throw, taking Force damage equal to the total damage you took while Demonic Retribution was active on a failed save or half as much damage on a successful one. In addition on a failed save, the enemy is pushed in a chosen direction for half your maximum Speed. 

If you current Hit Points are below half of your maximum Hit Points, the enemy makes their saving throw at Disadvantage. 

The save DC equals 10 plus your Constitution modifier and Proficiency Bonus.

Level 17: Unification of Two Souls

The unification of you and your demon's two souls has created a being capable of wielding terrific power. You gain access to multiple abilities as your Hit Points decrease that will allow you to endure any hardship: 

• If your Hit Points are below half of your maximum Hit Points: Whenever you make a successful attack, you regain 1 Focus Point. 
• If your Hit Points are below one quarter of your maximum Hit Points: Whenever you make a successful attack, you regain Hit Points equal to one roll of your Martial Arts die. 
• If you fall to 0 Hit Points: You can expend 5 Focus Points to regain 2d20 Hit Points. The cost for this ability increases by 1 Focus Point each time, and the cost resets on a Long Rest. 

You can use each ability Thrice per turn.