What is The Chained God?

When Piper and Annabeth go in search of the 'chained god', they find a life sized bronzed statue of Ares...bound in chains. On either side of the statue are two doorways with a monster's head carved over them. They soon realize that the statue ramps up fear in people and those around it will be infected. It is only when both girls face their fears that they are able to take the heart of the chained god.