The wait is over, the day has arrived, Xur is selling the Gjallahorn for the first time since the games early days. That's right, for a meagre 17 strange coins you too can have the most sought after weapon in the game. Xur can be found in the Tower Bar this week, which is located just below the hangar.

Gjallahorn has been a staple in Destiny's endgame content since Day 1, with many players refusing players to their group if they didn't have one. Raids like Crota's End amplified the weapons importance and legend as a full team of Gjallahorn equipped guardians could take down Crota in minutes on hard mode. 

The secret to Gjallahorn's strength lies in the wolfpack rounds which break off from the main impact and track their target. When they hit they do a large amount of damage themselves , so much so that Bungie has decided the weapon will be nerfed in patch 2.0 (The Taken King). Whether or not this has something to do with the rocket launchers sudden availability is still up in the air.