The feeling of not being who you feel you are is one of the worst. It's like being trapped and unable to escape. It is crushing and tormenting.
Although it seems that you can be anything in this magical world, you can't escape yourself even here. One similar feeling has been called Gender Dysphoria since the old world.
This condition is known as gender identity disorder and is quite common. It manifests in which a person feels disconnected between his biological and gender identity. People with Gender Dysphoria may feel trapped in a body that doesn't match their true selves. And this is not a rare phenomenon in the world of Spellfire too.
Here, in this magical world, there is a spell that can cause this to another being. The effect is so strong that it can make the creature lose his mind and suffer.
However, the effect is not permanent, as it can be canceled. The only thing that makes it difficult to heal from it is that the one who cursed it must cancel it himself.