Way of the Oni

Gozu the Night Terror, An Oni of Incredible power, once traveled the Iron Cage Summit in the guise of a legendary master monk. Using this guise, Gozu founded the Way of the Oni and taught others a unique tradition born of his own supernatural skill. Unfortunately, training his students could not subside the Onis Hunger, and after preying upon a small city below his monastery, Gozu was discovered and imprisoned in the mask of Oniborne. This legendary artifact serves as his prison to this day

Bonus Proficiencies

You gain proficiency in the Charisma (Deception) skill if you don't already have it, and you learn to speak, read, and write Giant or one other language of your choice. 

Wrath of the Oni

Your mastery of Ki allows you to empower yourself with the supernatural power of the Oni. As a bonus action, you can spend 1 Ki point to transform, taking on a demonic appearance with horns, strikingly white pupils and jet black teeth. When you do so, each creature of your choice that you can see within 10 feet of you must succeed on a Wisdom saving throw against your Ki save DC, or become frightened of you until the beginning of your next turn. 

You can remain transformed in your Oni form for 10 minutes. Your Oni form ends early if you choose to end it (no action required), or if you are incapacitated or die. 

While in your Oni form, you gain the following benefits:

Consume: When you make an unarmed strike, you can enlarge your jaw to bite and feed on the life essence of another. Once on each of your turns when you damage a creature with an unarmed strike, you regain a number of hit points equal to your proficiency bonus, provided you have less than half your hit points when you hit. 

Shapechange: as an action you can magically polymorph into a small or medium humanoid, or back into your demonic appearance. Other than your size, your statistics are the same in each form. Any equipment you are wearing or carrying isn't transformed. At any time for the duration of your Oni form, you can use your action to change your appearance in this way again.

Savage Strikes

When you spend Ki to use Flurry of Blows, the first unarmed strike you hit deals two rolls of your Martial Arts die, instead of one. If you use this feature while transformed with your Wrath of the Oni feature, after dealing additional damage with an unarmed strike, the creature must also make a Strength saving throw against your Ki saving DC, or be knocked prone. 

at 11th Level, the damage of this feature increases to three rolls of your Martial Arts die. 

Hunger Pains

Using your Ki to empower yourself with an Oni's supernatural strength has caused you to develop an unending hunger, similar to an Oni's desire for human flesh. As a bonus action, you can choose to reduce your hit points maximum by 5 to regain 1 Ki point. This hit points maximum reduction lasts until you finish a long rest or use the consume feature detailed below. 

Consume: Spend one hour eating remains of a recently slain humanoid to remove any hit points maximum reduction, including those given by curses or magical effects (such as a Mummy's rotting fist or Wights life drain) . Toi qualify, you must eat 10 % of your body weight from a humanoid that has died within the last hour. You can consume during a short rest. 

Oniborne

You've learned to unleash the full potential of your Oni form. When you use a bonus action to transform with the Wrath of the Oni feature, instead of spending 1 Ki point you can choose to spend 3 Ki points to empower your Oni form. Spending 3 Ki points unleashes your true potential providing the following benefits. 

• You gain all benefits from your Wrath of the Oni feature
• You can choose to change the damage type of your unarmed strike to Lightning Damage. 
• When a creature hits your with an attack, as a reaction, you can spend 1 Ki point to force the creature to make a wisdom saving throw against your Ki save DC. On a failed save, the creature takes lightning damage equal to four rolls of your Martial Arts die, and until the end of your next turn its speed is reduced by half. On a success, the creature takes half damage and is not slowed.