I got one from a run in my warlock in the first week. Was maybe the third run I'd done? To put that into perspective, I ran the echo chamber about forty times to get my gauntlets - my friend was helping me on his hunter and joined in, got them after about five runs. I'd actually try on a different character. *Also got the Solar Flayer Mantle after the second run of the new version of Dust Palace on my warlock.