Prophecy is delivered through visions of gay smelly gay and his poker friends but yes you shall go west and face the god who has turned. He winds up having to leave his mom behind in the underworld which is actually what he kept telling himself was his personal quest let alone whatever the World War 3 stuff was. "I did like that about Percy that feels very true to this whole Greek myth realm where like somebody's like listen you got to do this great thing for the world"