The Rusty Trophy is a 'monster drop' that was introduced during the Ratboy's Nightmare Update. It is one of the many collectibles that are needed by the players in order to complete the entries of the Itempedia of the Nightmare. The Rusty Trophy can be obtained as a possible 'rare' drop from the Path Gambler or the Golem Baron.
In appearance, it shares a similar appearance to that of the King of the Sea, except the head of the trophy has sprung off from the body, as seen by the coil between the head and the body. The crown is now made out of stone, instead of gold, and the rest of the body had been heavily rusted.
The Rusted Trophy does not have any usages in-game that will benefit the players, other than to be sold to a selling vendor at a selling price of 1,000,000 gold.