The Way of the Void Class for Dungeons & Dragons (D&D) Fifth Edition (5e)

Base Class: Monk

As the Jaws of the creature are about to rip him in half, the Human Monk stood perfectly still and merged with emptiness, ignoring all damage that was about to hit him. Defending his temple, a Shifter unleash a flurry of blows on his opponent, each strike empowered by a dark purple energy, ripping the Orc to pieces. A Deva hide behind a wall of energy preparing his next move, it will never know how the Half Elf managed to bypass its protection, bolting through the wall of force and the deva before delivering the final blow.

The monk who follows the Void Path exploits the power of nothingness in the slits of the very being. The monk adept in this school is able to fill the spaces between existence and non-existence, moving both physically and mentally through the fabric of the universe. The monks of Void spend their time of rest in deep meditation, during which their physical form begins to resonate with the essence of the void. They come to merge with the emptiness. As they remain in meditation in the void, they absorb its power in their essence of life (ki). The longer they remain in this state of meditation, the more they become a part of the Void, until all their ki is the essence of emptiness itself. They are then able to focus and use their new state of emptiness, moving through matter and striking with a life devouring energy, their time spend in nothingness expended their senses and their ability to manipulate Ki. After countless hours meditating on the void, they can even reach the True Void, the ultimate state that the Void can offer and decuplate their powers and abilities.

By the nature of the Void energy, many monks of Void act as fierce warrior against extraplanar entities, fiends or even gods, Void being one of the few things out of control from them.

Void Arts

When you choose this tradition at 3rd Level, you gain acces to the Void arts technique.

You know the Guidance and True Strike Cantrip, you can cast them as a Bonus Action for 1Ki points

You choose 1 Void Arts when you take this tradition, you learn additionnal Void Arts when you reach 6th, 10th, 14th and 18th Level.

Become Empty

You have learn to become empty in response to an attack. When you get hit by an attack, you can as a Reaction spend 2 Ki points to merge with the Void for a brief moment. You ignore the damage dealt by the triggering attack and are resistant to all damage until the beginning of your next turn.

Corrupting Ki

You know how to disturb the natural rythm of a creature Ki
When you hit a creature with an Unarmed Strike, you can spend 2 Ki to force a Constitution saving throw against your Spell DC. On a success you inflict the following effects :
You choose one ability check or saving throw, the creature have disadvantage on this saving throw for the duration.
Every time the creature suffer damage, it suffer your Martial art die as additionnal damage.

The Corruption last for 1 Minute or can be dispelled by a Remove Curse, a Greater Restoration or a Wish spell.

Devouring Aura

The aggressive nature of your Ki expend out of your body and can affect living creature in your proximity.

As an Action, you can expend Ki Points to activate Devouring Aura for a duration of 1 minute / Ki Point expended.

When a creature start his turn within 15 feet of you, you can force them to make a Constitution saving throw against your Ki DC. On a fail, the creature suffer your Martial art die as Force damage and you gain temporary hitpoints equals to the damage inflicted.

Extraplanar Bane

You learn how to disrupt a creature's Ki through the Void.

As an Action, you can spend 2Ki point to cast Bane. if the Creature is a Celestial, a Fiend, an Aberration or a Fey, they have disadvantage on their saving throw against the spell.

Resilient Mind

When a creature forces you to make a Intelligence, Wisdom or Charisma saving throw and you suceed, you can use your reaction to expend a Ki point and inflict your martial art die as Force damage to said creature.

Void Glare

As a Bonus Action, you can spend 1Ki point to gain True Sight within 60 feet for 1 minute. you can expend additionnal Ki points to extend the duration (1Ki/Minute)

Voidwalk

you can use your Ki to enter a special pace called the Voidwalk.
As a bonus action, you can use 1 Ki point to make your physical body merge with the void. You must immediately take your movement. While Voidwalking, you do not trigger attack of opportunity and you can move through material objects and creatures in your path up to your movement speed minus 5. (if your movement speed is 40, you can move through objects or creature up to 35 feet wide). You ignore magical barriers and any damage or effect from environnemental elements.

Free the Void

At the 6th level, you get the ability to imbue your attacks with the essence of the Void, unleashing its power in your target. 
When you hit with an Unarmed Strike or a Monk Weapon, you can spend up to 3 Ki Point to add 1D6 Force damage / Ki, up to 3D6 Force damage.
At the 17th level, you have reached the True Void. when you Free the Void, you use your martial art dice for damage instead and your strikes ignore Force resistance

Essence of the Void

at 11th level, the void become a intergral part of your being, you gain the following features :

When you hit a creature with a critical, you regain 1 Ki Point. You must be using your Unarmed Strike or a Monk Weapon. 
You gain Tremorsense on 30 feet and Blindsight on 15 feet.
You are immune to the charmed or Frightened condition from Celestials, Fiends, Aberrations or Feys

Champion of the Void

when you reach 17th Level, you have become a Champion of the Unyielding Force. Your time spent in total emptiness allowed you to reach the True Void.

You gain expertise on Perception and Insight

Your Tremorsense and Blindsight expend to respectively 60 feet and 30 feet and you can see perfectly in magical or non magical darkness up to 120 feet.

You gain resistance to Force damage.