There never was an invincibility cheat for AO. Never.
Edit(stupid tab button):
Thus, I don't think we'll ever know what is behind him...
End. (I think...)
Edit2: I've searched on google, and I've found this:
http://www.playstationalley.com/ps/oddw.htm
I must say that I don't trust that cheat... It never worked for me.
