Total Introjection

You attempt to mentally bond yourself to another humanoid's body. Your body enters a coma-like state, and the target must make an Intelligence saving throw. On a fail, their body also enters a coma-like state for the duration of the spell, and you enter the target's mindscape and take over the Ego. On the second turn of casting, once inside the their mind, the target must make a Wisdom saving throw. On a fail, you gain access to their thoughts and memories for the spell duration and assimilate their Superego. Then, on the third turn of casting, the target must make a Charisma saving throw at the end of their next turn. On a fail, you assimilate the Id and successfully bind your psyche to them. On a success at any point, you are forcibly made to reenter your body and cannot attempt this spell against this target again for 24 hours. A target can choose to fail any or all of the saves. If you are already possessing the target's body or are otherwise inside their mind in any way, the first save is considered an automatic success. Once you succeed the Ego stage, you cannot stop casting the spell unless the target succeeds a following saving throw, your bodies are moved to different planes from one another, or either of you die.

Once successful, your bodies and minds merge, and you gain the stats of the target. You replace any of your physical racial features with the target's. You gain any class features the target had, as well as learning any spells they know. You can choose to let the target's psyche take control at any point; otherwise, they are passively in the background- capable of speaking psychically to you or in a mental stasis. Physically, you count as one creature, and if the target's body were to die, this spell would end and you would split into separate bodies and your soul would return to your own body. Any spells that target one creature's mind only affect your consciousness, not your targets.

A Greater Restoration cast at 8th level or above ends this spell, and your bodies and minds separate.