Drow Transformation

You strike a target with a sudden flash of volatile, ancient transmutation magic. Make a ranged spell attack against a humanoid creature within reach. On a hit, the spell instantly fires and rewrites their biological and spiritual identity. The transformation is instantaneous and permanent.
The Transformation: The target’s skin turns to flawless obsidian, their hair turns white, and their original species traits are instantly erased and replaced with the Drow Lineage traits (Enhanced Darkvision 120ft, Fey Ancestry, and Drow Spell-casting).
The Darthiir Penalty: If the target is a Darthiir (surface elf), the shock of the forced mutation is so violent to their ancestral soul that they must succeed on a Constitution saving throw against your Spell Save DC or be Stunned until the end of their next turn.
Removal: Because the duration is Instantaneous, the effect is not ongoing magic and cannot be ended by Disguise Self, Remove Curse, or standard Dispel Magic. It can only be undone by a Wish spell, or by a highly complex, expensive reverse-ritual known only to the High Masters of Sorcere or the Matron Mothers.