I think that NEW item Duskblade may have a bugged interaction with QSS effect. I used it to clear Deathmark from Zed and the mark went away yet the nightfall stayed and cost me my life. I wanted to post to make sure that it was supposed to stay even through QSS.
It is supposed to be removeable by QSS Remember that Nightfall is triggered by auto attack, so if you used QSS after Zed's ult finished and gave you the deathmark, but before he landed an auto attack, then QSS would not have removed Nightfall, leading to the situation you describe.
Do you have a video of the incident, or have you tried to recreate the bug?
