Warframe has celebrated its first anniversary with free downloadable content. For a limited time, developer Digital Extremes is giving the 'Dex Furis' weapon to PS4 players of the free-to-play shooter without charge. To claim the DLC, users must log in to the game before April 21 and open the respective inbox message. The studio also unveiled the 'Excalibur Proto-Armour' skin, which is a reflection of the Tenno past and available for a limited time. Touted as the title's largest expansion to date, update 13 is a few weeks away from release. The upcoming update will introduce a new Warframe, a boss battle, additional weapons and Sentinels. Source Digital Spy.