Destiny: Rise of Iron marks the return of the fan favorite Gjallarhorn. This can be obtained through an exotic quest in the game for Year 3 Iron Gjallarhorn.
Before starting the quest in Rise of Iron, you have to make sure to get a Splicer key from Brood Mother wizard. They can be located around the Plaguelands fighting the Fallen.
Once you have managed to find a Splicer key and get a quest requiring you to scan an anomaly, head to Archon’s Peak. Try to locate a Patrol beacon with a ghost symbol there. If you can’t locate it, you will have to head back to orbit and then return there to see if it shows up on map.
The quest will require you to go to Archon’s Forge. Reaching it will result in a locked laser gate that can be opened with the splicer key. You will have to fight a room of fallen enemies with an elite captain to pick up a Hammer as a Relic. Once you are done, head down the stairs to reach a big room with a SIVA walker along with enemies. You can kill the enemies but steer clear of the SIVA Walker by stunning and scanning it. Scan the medallion to complete this step.
Talk to Tyra Karn to get instructions about getting more of the Iron medallions. These medallions can be found using the guide here. You can find these medallions in every patrol area of the Plaguelands and even in Felwinter Peak.
Once you are done with locating the medallions, head to Banner Fall and scan archives, library and blueprints all around it. This will trigger an event in which the tower defense system will go down and you will be alerted about an attack by the Fallen.
You will be required to dismantle two different bombs on the each side of Banner Fall. Once you are done with disarming the bombs, you will have to fight with a giant Fallen captain with the help of the Banner Fall defense system.
Completing this mission, return to the cryptarch who will ask you to get him 5 pieces of SIVA Cluster. You can follow this guide to locate every SIVA cluster, even if you need just 5 of them. Once you are done, you will have to locate pieces of the Ghorn on Earth. The mission starts in Steppes and ends in the Frontier map from Crucible.
You will reach a room at the end of the mission where Ghost will try to reconstruct the Ghorn while you have to save him from the horde of Fallen enemies.
Once you have the Ghorn, you can infuse it into the Iron Gjallarhorn and easily clear the horde of enemies by utilizing the heavy ammo crates scattered throughout the room.
Destiny: Rise of Iron is available now for the PS4 and Xbox One.