After finishing the final strike to get Thorn (The Chasm of Screams), the quest description that gets completed in the directory... wasn't completed. Usually after finishing a strike for a quest, you receive the rewards as soon as it says "Mission Complete". However, I never got Thorn, and the quest still says I need to complete the strike. I spent 3 hours soloing the whole thing up until the boss fight, where I had to get someone else to help me. My only guess is that Savathun's Song was killed quicker than the game anticipated, but killing the thing you set out to do should still warrant the reward. I used Celestial Nighthawk with bottom-tree Gunslinger as soon as it got to a little below half-health, killing it before it had time to activate its impenetrable shield and making me use Void charges to damage it. It's not the way you're supposed to kill it, sure, but it dies either way, and I don't want to spend another 3 hours just to kill it the "right" way. The quest itself only requires the strike to be completed, and that's exactly what I did. I did take a video of the activity summary to prove I actually completed the strike, which is included at the top of this post. My gamertag is SilkLeader1361 if that helps. It would be great if I could just have that quest completed remotely, without having to go through that whole ordeal again (501 kills spread over 3 hours ;o;) If anybody has a possible explanation to why the quest didn't complete even after completing the strike, feel free to reply. Thanks!