Is it permissible to undo magic if undoing it entails harming its perpetrator?

If breaking magic through legitimate means necessitates harming the sorcerer, then there is no blame in that. This is because he is like an assailant attacking one's person, who can only be repelled by killing him or harming him. The sorcerer's prescribed punishment in Islamic law is death, so inflicting a lesser harm upon him is permissible, a fortiori.