Take Margol's Gigantic Horn to Curator Thorius in Ironforge.
You expect me to believe a story like that? The real horn would have had my broken axe head still lodged into its surface.
Listen, take that obvious fake to Curator Thorius in Ironforge. If he can validate your claim, you will receive a proof of deed. Bring that proof back to me and I'll give you the key to the Searing Gorge.