Phantasmal Assassin

You are deeply connected to your phantasmal self, granting you the ability to confuse, distract and control using phantom versions of yourself.

Phantasms

When you choose this subclass at 3rd level, you gain the ability to summon an ethereal copy of yourself as an action or bonus action. This phantasm appears on your square, but moves and acts independently of you, has an AC equal to 10 + your INT modifier, and 1 hit point. You can summon up to a maximum of 2 phantasms at level 3. Phantasms may occupy your space without penalty. It has one attack per turn that deals 1d4 psychic damage that scales with your INT modifier and proficiency bonus.  Upon taking damage, a phantasm is destroyed.

If your phantasm occupies the same space as you (and only one may do so at a time), it provides half cover. If an enemy misses you due to the cover bonus, the phantasm takes the hit for you and is destroyed. Phantasms cannot move or act on the turn they are summoned, but they still provide the half cover bonus. Phantasms last until shattered or until dismissed as a bonus action. 

The maximum number of phantasms you may have active at once increases by one at 9th, 15th, and 20th level. If you already have the maximum number of phantasms and you summon another, you choose which one is destroyed. The Phantasms damage die increases to 1d6 at 12th level and 1d8 at 18th level. 

Phantasmal Detonation

At 9th level, you gain the ability to detonate your phantasms. When you have active phantasms, you may detonate them in one of three ways. Each method destroys all the phantasms you have summoned. The DC for the following abilities is 8 + your proficiency bonus + your INT modifier.

• As an action: All phantasms detonate into bursts of psychic energy. All creatures within 5 feet of a phantasm must pass a DEX saving throw or receive 1d6 + your rogue level psychic damage. Creatures who succeed on the save take half damage.

• As a bonus action: All phantasms detonate into brilliant flares of psychic energy, blinding nearby foes. Creatures within 5ft must make an CON saving throw. On a failed save, the creature becomes blinded until the end of your next turn. On a successful save, the next attack against that creature has advantage.

• As a reaction: After taking damage, you may use your reaction to detonate your phantasms. Pick one of the detonating phantasms and teleport to its location, you take psychic damage equal to your rogue level, meanwhile the creature who attacked you takes psychic damage equal to 1d4 x the amount of phantasms detonated.

Phantasmal Manipulator

At 13th level, you have mastered phantasms and are able to manipulate the battlefield to become a true menace. You gain the following abilities:

• Blink: As a reaction when you are attacked, you may teleport up to 30ft, leaving behind a phantasm as you do so. The attack is then resolved against the new phantasm's AC.

• Phantasmal Being: As a bonus action, you may render yourself invisible, as if under the effects of the Invisibility spell. It lasts for a number of rounds equal to half your INT modifier (rounded down). A phantasm appears in your space.

You have two charges to use these features, these charges reset on a long rest.

Phantom Entity

At 17th level, you are one with your phantasms, and they are one with you. Your phantasms now appear to be exact copies of your self, enemies cannot tell the difference between you or a phantasm unless they succeed an INT check on their turn or see you take an action. The DC for the INT check is 10 + your proficiency bonus + your INT modifier. During your turn you can spend a bonus action to swap with any of your active phantasms at which point all enemies who can see you make the INT check. Enemies who fail the INT check, and haven't seen you summon a phantasm or take an action do not know which copy of yourself you are and as such you count as hidden for the purposes of attack advantage. 

As a semi-phantasmal being you are semi ethereal, you gain resistance to non-magical piercing, slashing, and bludgeoning damage. 

Finally your sneak attack damage is now always psychic damage as you attack their very mind.