Through events such as an experiment gone wrong, a caster having their magic ripped from their being, hazardous divine punishment, or other means of the nature; these monks have been brandished with a power that is the anthesis of Magic. This energy allows them to use the power of others, be it their mana or even vitality, and wield it for themselves in various manners. Forever marked as those who use the life essence of others to fuel themselves onward. 
These monks often come from nefarious origins, their new state the result of malicious experiments or meddling with mystic forces beyond their scope.
Not all are so insidious in mind however, and may just be the victim of a freak accident; or perhaps have reflected upon their wrongdoings as a result of this new life. 
Regardless of morality, all Void Monks are alike in their capacity. A broad capacity for havoc. 

Ravenous Contact

At 3rd level, when you land an unarmed strike against a creature w/ unused spell slots, you can steal their magic to amplify yourself. Gain the following features.

Hungering Strike - When you land an unarmed strike on a creature, you can absorb an unused spell slot from them. This can grant you one of an assortment of bonuses. 
See ability for details. 

Thirst of the Empath - When touching a creature, you can choose to read their emotions and state of mind.
The creature must make a Charisma Saving throw against your DC or have their most prominent emotions revealed to you. Can be done 3 times per long rest.

Negative Wave

At 6th level, you gain the ability to expel your latent energy in an unfocused blast; as well as understanding the magic of your enemies better. You gain the following features.

Negative Wave - Unleash the anti-magic energy in your body in a ruthless aura; stealing the vitality of your foes for yourself. See ability for details.

Resistance of the Null Blooded - You are immune to magic, spells or otherwise, that cause life drain or illness-like effects. Such as by Vampiric Touch or Contagion.
As well as gaining advantage against any spell that requires you to make a Constitution or Dexterity saving throw.

Wrath of the Broken

At 11th level, you gain better control of the energy within yourself, allowing you to focus it into more accurate attacks; as well as disrupt the attacks of others. Gain the following. 

Seekers Eruption - Using your negative aligned energy like for a beam attack, smite your foes from afar. See ability for details.

Unyielding Stance - Your deflect missiles ability improves in complexity. It can now effect ranged attack spells targeting you alone.
When using deflect missiles against spells in this fashion, you can double the result of the roll to negate damage. 
Examples of this would be firebolt, chill touch, or acid arrow. 

Form of Absolution

At 17th level, you learn the ability to assume an aura comprised of the energy held within yourself. You gain the ability State of Absolution.
As a bonus action, wreathe yourself in a negative aura. While in this form..

- Spells below 5th level are nullified and absorbed by your aura, granting your temp hp equal spell level.
- Unarmed strikes, as well as your Void abilities, gain a bonus to damage equal to your CHR and WIS bonuses combined.
- Gain an additional +15 to movement speed

This form lasts until one minutes passes, you are incapacitated, or you die. You can end the form on your own as a bonus action.
When your form ends via time running out or you choosing to, a pulse of energy is released from you concurrent with the amount of magic neutralized by your form. 
Explosion deals 4d6 force damage innately, plus an additional 1d6 for every spell neutralized, with a radius of 30ft; this damage can not be resisted, but you can choose which creatures are damaged within the radius.