This is an adaption of the Mystic class, which is not feasible as a standalone class currently. It is way more balanced and quite interesting, specifically for rouges.

To be more precise, this is an adaption of the "Avatar" subclass of the mystic. It is highly advised to have a look at the Mystic UA class.

Balancing wise, this subclass has less options and less capabilities. There are no regulations regarding the amount of Psi Points you may spend, but you may not get them back. You can only have one feature active at the same time. Also, you will have to sacrifice points to enhance your int-score, to have more power full abilities.

All credits for the specific details of the Features go to WOTC. This adjusted the unpopular mystic to be a subclass, which is actually usable. It is highly adjusted but the base idea is from WOTC.

Psionic Disciplines

A psionic discipline is a rigid set of mental exercises that allows a mystic to manifest psionic power. A mystic masters only a few disciplines at a time.

Each discipline costs a certain amount of psi points to activate. These points are consumed when the ability is activated. You regain any spend Psi Points upon finishing a long rest. Only one ability can be activated at a time, in addition to your psionic focus. Some abilities require additional concentration. The same rules apply to these as to spells.

Each discipline has a passive ability called "Psionic Focus", which has no activation cost. You can have one of these abilities active at any time. Changing the focus costs one action.

You gain 2 Disciplines if you choose this subclass and again at 9th, 13th and 17th level.

Crown of Despair

You have learned to harvest seeds of despair in a creature’s psyche, wracking it with self-doubt and inaction.

Psychic Focus. While focused on this discipline, you have advantage on Charisma (Intimidation) checks.

Crown of Disgust

You cause a creature to be flooded with emotions of disgust.

Psychic Focus. While you are focused on this discipline, the area in a 5-foot radius around you is difficult terrain for any enemy that isn’t immune to being frightened.

Crown of Rage

You place a mote of pure fury within a creature’s mind, causing its bloodlust to overcome its senses and for it to act as you wish it to.

Psychic Focus. While you are focused on this discipline, any enemy within 5 feet of you that makes a melee attack roll against creatures other than you does so with disadvantage.

Mantel of Command

You exert an aura of trust and authority, enhancing the coordination among your allies.

Psychic Focus. While focused on this discipline, when you end your turn and didn’t move during it, you can use your reaction to allow one ally you can see within 30 feet of you to move up to half their speed, following a path of your choice. To move in this way, the ally mustn’t be incapacitated.

Mantle of Courage

You focus your mind on courage, radiating confidence and bravado to your allies.

Psychic Focus. While focused on this discipline, you and allies within 10 feet of you who can see you have advantage on saving throws against being frightened.

Mantle of Courage

You tap into a well of primal fear and turn yourself into a beacon of terror to your enemies.

Psychic Focus. While focused on this discipline, you have advantage on Charisma (Intimidation) checks.

Mantle of Fury

You allow the primal fury lurking deep within your mind to burst forth, catching you and your allies in an implacable bloodthirst.

Psychic Focus. While focused on this discipline in combat, you and any ally who starts their turn within 10 feet of you gains a 5-foot increase to their walking speed during that turn.

Mantle of Joy

You tap into the joy within you, radiating it outward in soothing, psychic energy that brings hope and comfort to creatures around you.

Psychic Focus. While focused on this discipline, you have advantage on Charisma (Persuasion) checks.

Base Disciplines

As you choose this Subclass, you gain one Discipline, which doesn't count towards your other disciplines chosen.

Psionic Restoration

You wield psionic energy to cure wounds and restore health to yourself and others.

Psychic Focus. While focused on this discipline, you can use a bonus action to touch a creature that has 0 hit points and stabilize it.

Telepathic Contact

By channeling psionic power, you gain the ability to control other creatures by substituting your will for their own.

Psychic Focus. While focused on this discipline, you can telepathically speak to any creature you can see within 120 feet of you in this manner. You don’t need to share a language with the creature for it to understand your telepathic messages, but the creature must be able to understand at least one language or be telepathic itself.

Psionic Talents

A psionic talent is a minor psionic effect you have mastered. At 3rd level, you know one psionic talent of your choice. You learn one additional talent of your choice at level 6 and again at level 9. 

Psionic talents are minor abilities that require psionic aptitude but don’t drain a mystic’s reservoir of psionic power. Talents are similar to disciplines and use the same rules, but with three important exceptions:

• You can never use your psychic focus on a talent.
• Talents don’t require you to spend psi points to use them.

Beacon

As a bonus action, you cause bright light to radiate from your body in a 20-foot radius and dim light for an additional 20 feet. The light can be colored as you like. The light lasts for 1 hour, and you can extinguish it earlier as a bonus action

Blade Meld

As a bonus action, a one-handed melee weapon you hold becomes one with your hand. For the next minute, you can’t let go of the weapon nor can it be forced from your grasp.

Blind Spot

As an action, you erase your image from the mind of one creature you can see within 120 feet of you; the target must succeed on a Wisdom saving throw, or you are invisible to it until the end of your next turn.

Delusion

As an action, you plant a false belief in the mind of one creature that you can see within 60 feet of you. You can create a sound or an image. Only the target of this talent perceives the sound or image you create.

If you create a sound, its volume can range from a whisper to a scream. It can be your voice, someone else's voice, a creature's roar, a musical instrument, or any other sound you pick. It lasts for 1 minute.

If you create an object, it must fit within a 5- foot cube and can’t move or be reflective. The image can't create any effect that influences a sense other than sight. The image lasts for 1 minute, and it disappears if the creature touches it.

Energy Beam

As an action, you target one creature you can see within 90 feet of you. The target must succeed on a Dexterity saving throw or take 1d8 psychic damage. It perceives the damage as any other type of your choice, using this damage for resistance, immunities and vulnerabilities.

The talent’s damage increases by 1d8 when you reach 5th level (2d8), 11th level (3d8), and 17th level (4d8).

Light Step

As a bonus action, you alter your density and weight to improve your mobility. For the rest of your turn, your walking speed increases by 10 feet, and the first time you stand up this turn, you do so without expending any of your movement if your speed is greater than 0.

Mind Meld

As a bonus action, you can communicate telepathically with one willing creature you can see within 120 feet of you. The target must have an Intelligence of at least 2, otherwise this talent fails and the action is wasted.

This communication can occur until the end of the current turn. You don’t need to share a language with the target for it to understand your telepathic utterances, and it understands you even if it lacks a language. You also gain access to one memory of the target’s choice, gaining perfect recall of one thing it saw or did.

Mind Slam

As an action, you target one creature you can see within 60 feet of you. The target must succeed on a Constitution saving throw or take 1d6 force damage. If it takes any of this damage and is Large or smaller, it is knocked prone.

The talent’s damage increases by 1d6 when you reach 5th level (2d6), 11th level (3d6), and 17th level (4d6).

Mind Thrust

As an action, you target one creature you can see within 120 feet of you. The target must succeed on an Intelligence saving throw or take 1d10 psychic damage.

The talent’s damage increases by 1d10 when you reach 5th level (2d10), 11th level (3d10), and 17th level (4d10).

Mystic Charm

As an action, you beguile one humanoid you can see within 120 feet of you. The target must succeed on a Charisma saving throw or be charmed by you until the end of your next turn.

Mystic Hand

You can use your action to manipulate or move one object within 30 feet of you. The object can’t weigh more than 10 pounds, and you can’t affect an object being worn or carried by another creature. If the object is loose, you can move it up to 30 feet in any direction.

This talent allows you to open an unlocked door, pour out a beer stein, and so on.

The object falls to the ground at the end of your turn if you leave it suspended in midair.

Psychic Hammer

As an action, you try to grasp one creature you can see within 120 feet of you, with a hand crafted from telekinetic energy. The target must succeed on a Strength saving throw or take 1d6 force damage. If it takes any of this damage and is Large or smaller, you can move it up to 10 feet in a straight line in a direction of your choice. You can’t lift the target off the ground unless it is already airborne or underwater.

The talent’s damage increases by 1d6 when you reach 5th level (2d6), 11th level (3d6), and 17th level (4d6).

Avatar of Healing

Also at 3rd level, you project an aura of resilience. While you aren’t incapacitated, each ally within 30 feet of you who can see you regains additional hit points equal to your Intelligence modifier (minimum of 0) whenever they regain hit points from you.

Avatar of Battle

Starting at 6th level, you project an inspiring aura. While you aren’t incapacitated, each ally within 30 feet of you who can see you gains a +2 bonus to initiative rolls.

Psionic Speed

While you aren't incapacitated, each ally within 30 feet of you who can see you gains a +2 bonus to initiative rolls.

Avatar of Speed

Starting at 14th level, you project an aura of speed. While you aren’t incapacitated, any ally within 30 feet of you who can see you can take the Dash action as a bonus action.