Before you can start this exotic quest you have to complete the main story of Rise of Iron. You can check this in the menu under record book.
Timecode links will take you to Youtube
STEP 1 Anomaly Patrol Mission (00:25)
Drive to the Archon’s Keep and pick up the anomaly patrol mission to start off the exotic bounty for the Gjallarhorn Year 3.
This patrol mission will take you to Site-6 to a Spider Tank that you have to defeat. Scan the environment behind him to progress to the next step.
STEP 2 Talk to Lord Saladin and Tyra (03:03)
Back at the Iron Tower, talk to Lord Saladin and Tyra to get the next quest step.
STEP 3 Collect 7 Medallions (03:50)
Follow the video to find all 7 Medallions spread across the Plaguelands and the Iron Tower.
STEP 4 Talk to Tyra (10:28)
Talk to Tyra in the Iron Tower after you collected the Medallions.
STEP 5 Deafeat Iliksis (11:09)
You will get a new mission on earth that will involve 2 wave segments and a boss battle with Iliksis.
The 2 waves are respawn restricted and they are fairly hectic. So bring your best gear and watch out for explosive Shanks.
After killing Iliksis you can move on to the next quest step.
STEP 6 Talk to Tyra (11:39)
Tyra will tell you to collect 5 Dormant SIVA Clusters.
STEP 7 Collect 5 Clusters (12:06)
Follow the video to find 5 Clusters. During the mission “The Walls Come Down” you can easily collect 5 of them on your way.
STEP 8 Return to Lord Saladin (15:01)
Collect the final mission from Lord Saladin
STEP 9 Final Mission (15:36)
Your last mission will take you to another multiplayer map and yet antoher wave section. After you completed it, you can pick up the Gjallarhorn Year 3 and complete the mission with it by destroying the 2 Tanks.
Rocket Launcher ammo is all over the place like it’s christmas, so enjoy it while you can 🙂
INFUSIN THE IRON GJALLARHORN (17:09)
You can now infuse your year 3 Gjallarhorn with the Iron Gjallarhorn if you want to give it a nice new paintjob.