I did some solo in nyzul a while back looking or DNC dagger to unlock the WS. I did somewhere in the range of 15 solo trips from 96-100 as mnk. I would get one of the flee drinks from the temp items box and go. I got one "same time" lamp floor that I couldn't manage to complete and had to leave before time was up. On every other run I would reach the boss and get in 5+ more floors of progress just looking for nm's. So either I was truly lucky or you are terribly unlucky to not be able to. But either way, it can be done easily solo. Just sayin'