i dont remember what exact quest, but it is in dragonspyre. The quest requires you to find the 8 shards of the dragonrider staff, which were scattered through out the spiral(i could be wrong though, so if i am feel free to correct me)
I have been looking and can't easily find the answer to this...what are the obsidian chests for and why can't I open them? Is it only for certain people? I've seen them on all levels.
The Obsidian Chests are for a DragonSpyre quest, which requires you to go back to where each of the chests are at, and open them. To open some of them, you may have to battle the opponents there to get to the chest, but until then, don't worry about them.