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 "Awakened" 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 specifics of the Features go to 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. Only one ability can be activated at a time, in addition to your psionic focus. Even if an ability says, that you have to spend x amount of psi points, you can spend up to 7 points on a single ability. However, if not specified otherwise, this does not change the effects.

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.

Some abilities require additional concentration. The same rules apply to these as to spells. The time indicates how long the ability remains active with concentration maintained. While you have an ability with concentration active, you cannot activate another ability until you cancel the concentration with a bonus action. 

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

Aura Sight

You refocus your sight to see the energy that surrounds all creatures. You perceive auras, energy signatures that can reveal key elements of a creature’s nature.

Psychic Focus. While focused on this discipline, you have advantage on Wisdom (Insight) checks.

Intellect Fortress

You forge an indomitable wall of psionic energy around your mind—one that allows you to launch counterattacks against your opponents.

Psychic Focus. While focused on this discipline, you gain resistance to psychic damage.

 

Mantle of Awe

You learn to use psionic energy to manipulate others with a subtle combination of psi and your own, natural charm.

Psychic Focus. While focused on this discipline, you gain a bonus to Charisma checks. The bonus equals half your Intelligence modifier (minimum of +1).

Mental Disquiet

As you learned to use your inner, psychic strength, you feel yourself being quite restless. You feel that it is hard to loose your focus and rest. Sometimes, you just can't loosen up enough, to rest successfully in a short period of time.

When finishing a short rest, you have to succeed a DC10 + (amount of Psi Points spend divided by 3) or regain no expended Psi Points.

Precognition

By analyzing information around you, from subtle hints to seemingly disconnected facts, you learn to weave a string of probabilities in an instant that gives you extraordinary insights.

Psychic Focus. While focused on this discipline, you have advantage on initiative rolls.

Psychic Asault

You wield your mind like a weapon, unleashing salvos of psionic energy.

Psychic Focus. While focused on this discipline, you gain a +2 bonus to damage rolls with psionic talents that deal psychic damage.

Psychic Disruption

You create psychic static that disrupts other creatures’ ability to think clearly.

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

 

Psychic Inquisition

You reach into a creature’s mind to uncover information or plant ideas within it.

Psychic Focus. While focused on this discipline, you know when a creature communicating with you via telepathy is lying.

Psychic Phantoms

Your power reaches into a creature’s mind and causes it false perceptions.

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

Base Discipline

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

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 gain the ability to use your Telepathy class feature with up to six creatures at once. If you don’t have that feature from the mystic class, you instead gain it while focused on this discipline.

Third Eye

You create a third, psychic eye in your mind, which you cast out into the world. It channels thoughts and knowledge back to you, greatly enhancing your senses.

Psychic Focus. While focused on this discipline, you have darkvision with a range of 60 feet. If you already have darkvision with that range or greater, increase its range by 10 feet.

Psionic Talents

A psionic talent is a minor psionic effect you have mastered. At 1st level, you know one psionic talent of your choice. You learn additional talents of your choice at higher levels; when that number goes up for you, choose a new talent.

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.
• Talents aren’t linked to Mystic Orders.

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).

Telepathy

Your mind awakens to the ability to communicate via telepathy. 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. The creature then can answer you telepathically.

Mystic Talent

At 9th level, you gain proficiency with two of the following skills of your choice: Animal Handling, Deception, Insight, Intimidation, Investigation, Perception, and Persuasion.

You also learn to use your psychic ability to enhance you attacks and gain the Hone the Blade feature.

Hone the Blade

Starting at 9th level, you can spend psi points to augment your soul knife’s attack rolls and damage. You gain a bonus to attack and damage rolls with your soul knives depending on the number of psi points spent, as shown on the table below. This bonus lasts for 10 minutes.

• 2 Psi Points: +1
• 4 Psi Points: +2
• 7 Psi Points: +4

Psionic Surge

Starting at 13th level, you can overload your psychic focus to batter down an opponent’s defenses. You can impose disadvantage on a target’s saving throw against a discipline or talent you use, but at the cost of using your psychic focus. Your psychic focus immediately ends if it’s active, and you can’t use it until you finish a short or long rest.

You can’t use this feature if you can’t use your psychic focus.

Spectral Form

At 17th level, you gain the ability to become a ghostly figure of psionic energy. As an action, you can transform into a transparent, ghostly version of yourself. While in this form, you have resistance to all damage, move at half speed, and can pass through objects and creatures while moving but can’t willingly end your movement in their spaces. The form lasts for 10 minutes or until you use an action to end it.

Once you use this feature, you can’t use it again until you finish a long rest.