Base Class: Rogue
Long have you studied the ideals of psychic mastery. You poured over what illusory manuscripts you could get your hand on, and dabbled in small illusory spells to aid in your wanderings. The gift has always been within you, and your pure willpower brings forth aetherial phantasms - illusions so strong they can interact with the corporeal world. However you came upon the need for these magics, your deceitful ways have found harbor in illusory trickery. Besides, two is always better than one.
Illusory Understanding
You have picked up a few Illusory Magic tricks along your journeys. You gain access to the Minor Illusion cantrip, which may be used at will. You also learn the spells Disguise Self and Silent Image, and may use these spells 1{{modifier:int}} times per day.
Summon Phantasm
Starting at 3rd level, you gain the ability to summon a slightly glowing ethereal phantasm that takes the exact shape of your character. This phantasm spawns with half of your current HP, and an Armor Class of (10 + {{modifier:int}}. As a bonus action on your turn you may make an extra attack from the phantasm's position. Your phantasm spawns wielding one of your choice of your currently equipped weapons. This attack may activate your Sneak Attack feature if you or an ally are within 5 ft. of the enemy you are attacking. Either you or your phantasm may utilize it, but both cannot on the same turn. The same is applicable to magical effects that activate on an attack.
Deja Vu
Starting at 9th level, when you and your illusion successfully hit the same target, they take an initial 1d10 {{modifier:int}} psychic damage.
Phantasmal Guard
Beginning at 13th level, you gain a deep connection to your phantasm that allows you to transfer damage that you would take to your phantasm instead. As a reaction, you may choose to transfer the full amount of damage that would be done to you from one attack to your phantasm instead.
Astral Mastery
Starting at 17th level, you begin to master astral magics. So hardened is your arcane will, you gain an understanding of microcosmic energy waves, and can transmit your physicality through the Astral Plane to swap places with your phantasm, using your reaction in combat. You may activate this ability as a reaction when you or your phantasm is attacked, causing the other to swap places with the attacked and be attacked instead.
There are typo due to the use of snippet code in description int the Illusory understanding, Summon Phantasm and Deja vu feature.
for the phantasmal guard feature, what happens if the full amount of damage exceed the phantasm hp, are the leftover damage carried to you, like with polymorph and druid wildshape ?
Also, the Astral Mastery feature, I think it is very cool, but you can already transfer all the damage as a reaction thanks to phantasmal guard, so isn't the ability to exchange place as a reaction to avoid damage repetitive?