Voldemort never really had a downfall in Goblet of Fire. Infact he was revitalized and all Harry had left in protection was his wands core which matched Voldemort's. What is funny about this is that if Harry did not have the conection to Voldemort through his scar the Holly pheonix feather 11 inches that matched Voldemorts core. However Harry escaping because of Priori Incantantam was not Voldemort's demise, he still lived and now his weakness could be prevented using another wand. His demise comes from mistaken ownership of the Elder Wand