Tainted polymorph V0.04

Tainted polymorph is a ritual of round 10-feet Mirrors pointed to each other in an angled manner, Salt placed around the mirrors and spiraling into the middle in other smaller circles connected in straight curved lines, the circle should start at least 10 feet away from mirrors and end in the center of the reflective square, blood must be written on the mirrors and inside the salt circles, the participant must be in the middle.

(Optional step) a scroll of names of those who could remember him.

Dc16
For success or failure.

On success, the player will become any creature of their desire with an intelligent scorer higher than 9, or any race that they want but this will cause the player to change the race of their character or role a new character sheet if they so desire, including class change and everything but if the character wants a party or other NPCs to remember him use the scroll if not all NPCs think your old character is dead and the player characters if unsuccessful on intelligence save will believe your character is dead.

DC 15
For the party or NPCs to resist the ritual or not.

On failure, if a player character uses said spell or NPC, the character would begin to unwind into a tangled mess of limbs eyes, and ears approximately half of the size of their current body weight sprouting into their environment and warping into the ground, creating a landscape of assimilated flesh into the building or land growing fleshy organisms that resemble plant life, player character becomes evil in NPC unless a Dispel magic is used on him.

Dc18
For success or failure of the dispel.

DMs should note that this spell should be only given through patrons or through forbidden knowledge that hints or straight up says this is dangerous.
Also, it is up to the DM's discretion of how permanent it is, with anti-magic fields and dispel-magic and such.

All materials are consumed.