Way of the Undead Slayer

An elite force of the Holy Land of Asdera, the Slayers follow the forbidden Way of Undead Peril, a path that harnesses the necromantic forces of the enemy to fuel the power of the user against their enemies, particularly undead. Only a select few being chosen to follow this path, Slayer Monks train to absorb and cleanse the life force of undead that they meet to eradicate the undead plague from the world. This skill is extended to draw energy from their surroundings and purify it to use as ki, displaying their desire to complete their sacred mission at all costs.

Purged Soul

At 3rd level, you gain advantage on Constitution saving throws against effects that would change your basic creature type, such as lycanthropy or vampirism.

Life Absorption

When you choose this tradition at 3rd level, you have learned the basics of the core forbidden Purger technique and can draw ki from your surroundings to fuel your own power. You can use Flurry of Blows, Patient Defense, or Step of the Wind once per long rest without using a ki point. When you use Step of the Wind, your jump distance remains doubled for 1 minute.

Life Extraction

At 6th level, you've reached the next step in draining your surroundings of ki. When you kill a creature with a challenge rating of at least 2 with an attack that used ki points, you can extract its life force just before the moment of death, purify it, and wrap it around your attacks. For 1 minute, your melee unarmed and monk weapon attacks deal an extra 1d6 radiant damage and count as magical for the purposes of overcoming immunity and resistance; non-legendary undead are vulnerable to this damage. When you attack a creature while the bonus is in effect, they can't regain hit points until the start of your next turn as you unravel minute amounts of their ki. The damage die changes as you gain monk levels, as shown in the Martial Arts column of the Monk table. You have two uses of this feature, replenished every long rest. At 11th level, your study of undead allows you to weaken even legendary undead with the stolen ki; legendary undead become vulnerable to radiant damage from this feature.

Withered Countenance

By 11th level, your close experience with the forces of undeath and constant interaction with their life energy has rendered you resistant to necrotic and radiant damage at the cost of your physical appearance. You suffer disadvantage for Charisma (Persuasion) and Charisma (Performance) checks. 

Life Disruption

At 17th level, your interactions with the ki of others have given you an exclusive insight into the life force of nearly all beings. When you make a melee attack against a creature, once per long rest, you can spend 6 ki points and take one level of exhaustion. The creature takes radiant damage equal to double your Monk level as you abruptly unravel and purge part of its life force. If the creature is undead, it is vulnerable to this damage. If this feature kills the target, you can redirect the remainder of their life force to monsters of undeath surrounding you; all undead within 20 feet of the target takes damage equal to the damage the target took minus the target's former current hit points (the amount of leftover damage from the feature).