The North Line update has added plenty of new content in ARC Raiders, and the Flow Controller and Magnetron are leaving many players puzzled.
If you have been completing the Stella Montis quests, you'll need both. Both Exodus items are available from the Stella Montis map, but they don't have a guaranteed spawn point. To make matters worse, their spawns appear to be quite rare to begin with, and they can already get looted on a raid if you're unlucky.
