Way of Self-Affliction

There are a few strange groups of people who found pleasure in pain. They would inflict pain to themselves on a regular basis to appease their idols, taking small parts of themselves to cleanse their sins and their soul. This monastery train one's fortitude to sustain pain and turn it into amplified strength. These monks would enter battle with glee, knowing their enemies would not show mercy to them, and excited when they feel their weapons or fists hit their newly blessed body, only to reflect back that same pain to them.

Icon of Resilience

At 3rd level, your training has gained you the ability to not fear pain and be able to withstand it. Your gain max hitpoints equal to your monk level. This bonus doubles at 6th, triples at 11th, and quadruples at 17th.

Level Prerequisite	Bonus to Max Hitpoints
3rd	1 X monk level
6th	2 X monk level
11th	3 X monk level
17th	4 X monk level

You would also have proficiency with whips and flails and counts as monk weapons.

Power in Pain

Starting 3rd level, by taking damage, you can transfer that pain into your own strikes. When you hit a target with a melee monk weapon attack, you can expend 1 ki point to deal bonus damage equal to your martial arts die per 10 hitpoints you are missing (max 5 dice). 

Exsanguination

Starting at 6th level, you gain the following abilities:
Exsanguinate the Sin. Using an action, you can expend 3 ki points to gain a 20ft radius of a crimson red glowing aura around you. For 1 minute, when a creature starts their turn within the aura or enters it for the first time of that turn, they can choose to end a condition they are under as their sins are vanquished. If so, you lose hitpoints equal to your martial arts die. The aura ends early when you end it with a bonus action or if you are knocked unconscious.
Exsanguinate the Unwilling. When you use Power in Pain on a creature, you can expend an additional ki point to regain hitpoints equal to half the total damage dealt.

Sanguine Blessing

When starting at 11th level within this monastery, if you're at half of your total hitpoints or below, your shedded blood glows bright as you are blessed with newfound power. While in this threshold, whenever you are hit by a melee attack, the attacking creature will take acid damage equal to your martial arts die (the attack that takes you to the hitpoint threshold would not trigger the acid damage). Also while your hitpoints are at this threshold, all of your unarmed strikes and melee monk weapon attacks would deal bonus damage equal to your wisdom modifier.
Additionally, if you hit to 1 or lower hitpoints for the first time after a long rest, your friends feel a soothing touch of Death that eases their fear of it. Friendly creatures within 60ft of you would gain temporary hitpoints equal to your martial arts die plus your wisdom modifier. They can not gain this benefit a second time until you finished a long rest.

Death’s Door

Starting at 17th level, the sounds of hoove steps and the ringing of bells gives you a rush of adrenaline, wanting to afflict as much pain to others as possible while also having any final tastes of that same pain. If you take damage that brings you to 0 hitpoints, you instead would be on 1 hitpoint. While at 1 hitpoint, whenever you hit with a melee monk weapon attack, you deal maximum damage(this also applies to the bonus damage from Power in Pain).
Additional, when you take damage while on 1 hitpoint, you must make a DC 15 constitution saving throw to stay at 1 hitpoint. Repeating the save will increase the DC by 1. The DC to the save will restart after a long rest.