Every Tuesday, Tyra Karn will be waiting for you at the Iron Temple in Destiny: Rise of Iron to give you a quest that rewards you with a new Iron Lord Artifact. Completing this quest and obtaining the Artifact requires you to perform noble deeds in the Plaguelands, and no other information is provided aside from that. Here’s how you can get your ‘noble deed’ count up, and claim that Artifact from her:
Do patrols – Doing a patrol in the Plaguelands will fill up your bar by about 4%, so grab those whenever you can.
Do public events – Public events seem to give you more credit than patrols, and you can grab these in the Giant’s Husk where a Perfected Walker will sometimes show up, or in the Archon’s Keep, where you have to defend a Warsat.
Archon’s Forge victories – This seems to be the quickest way to fill up your bar, so I recommend heading into the Archon’s Forge and use up your SIVA Offerings if you want to focus on getting your noble deeds completed.
You can check your progress bar by looking at the quest details in your menu. Don’t forget that only activities completed in the Plaguelands will count for the new Rise of Iron quest. Once you’ve completed the bar, head back to the Iron Temple and choose a new Iron Lord Artifact from her.