Instructions
Quit "Castle Crashers" if you're playing it. Return to the PlayStation 3 main menu.
Select the "PlayStation Network" icon and then "PlayStation Store."
Hit "Search" and then type in "Castle Crashers."
Choose the "Necromantic" DLC and then select "Download." Wait for the download to complete. Once it's done, it will automatically install the DLC.
Start "Castle Crashers." From the character selection screen, choose either the necromancer or the wizard knight.