My feedback is for the Taken Champion, Stirok, in the Rocketyard. I would suggest relocating this adversary to a different location. On Earth, the Skywatch and Divide are the other locations for Taken Champions. These areas work because you can see the whole area and find the Taken Lieutenants to trigger the event.
All encounters require that you wait for the Champions. On top of that the Rocketyard has many obstructions that prevent you from seeing the Taken Lieutenants that appear. Another complication is that there are many Fallen that appear sporadically throughout the area, so it takes some determination to find the Taken Lieutenants. The Rocketyard encounter seems to have the same duration as the other areas, but with a far more dense and obstructed area. Therefore, by the time you find the Taken Lieutenants the event will disappear.
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I finally finished that ridiculously dumb quest after having only stirok to kill for two weeks. Noone is going to help you out for some odd reason either, and people rarely show up in the rocketyard. I figured out that if you wait for the first two lieutenants to spawn, or even all three, then go and take them out with a sword, it is easier to find all three as well as have time to kill stirok himself. I used a high impact sniper rifle and my gunslinger with celestial nighthawk. Try to only focus on stirok and not too much on the adds. I got lucky and two random people ran into the rocketyard and helped me out but I could have beaten him solo. Also, try to get him to spawn at the back of the rocketyard it is alot easier than when he spawns at the entrance to the rocketyard.