I've noticed a lot of people looking for help with weekly heroic/ nightfall strikes so I thought I would post a brief guide on how to approach the all of the boss fights in each of strikes (except Valus Tauarc because I suck at that fight, but feel free to post any strategies for that fight below, as well as additional strategies to the fights that I do address) hopefully these tips will make these fights more manageable, (and even soloable if you like that sort of thing). So here goes Devils Lair -Refinery After deploying Ghost, there is a cave to your left that glows green. The back of this cave is the safest place to be during these waves, and nothing but a few thrills will chase you back there. Fight it out from there. -Walker As soon as you enter the outdoor area, look to your left. About 50 yards or so away there should be a building whose roof is about the same height as the ground you are standing on. This roof is a great place to snipe the walker from, as it has scattered clutter that protects you from the walkers cannon blasts. -Sepiks Prime As soon as you enter the area where Sepiks is, there is a room to your left. This room is the safest place to battle Sepiks from, as it provides lots of cover, provides views to more than half of the places that Sepiks will spawn, and it is rare that enemies will ever follow you in there. Hope this helps. I will make separate posts for each of the remaining strikes.( read the replies)