I have ALWAYS maintained that the Destroyer is Ariel, despite the ambiguoity of his title H'rayaka...has anyone ever considered that maybe Salamander is the Destroyer? Seeing as everyone is pretty unanimous in believing Seresh is Salamander (which I also agree with), would that not make her a kasanda (futureteller), as only deformed temple guardians have that power? Could she not be foreseeing so much, Ariel implementing the tortuous methods, and then leading her to be the Destroyer?? I don't know please add to this and explain your disagreements/theories also!
If not that, then I really am starting to believe Dameon is the Destroyer, I don't know how or when Ariel factors into it, but since TS and Dameon's random appearance on the road it really started making sense to me, and he ALWAYS shields himself from Elspeth which I know could be out of his trying to hide his love for her but I also think could be him trying to hide his hatred...possibly borne of her obvious love for Rushton....gah!...contribute your theories guys!