I need to play it a bit more to figure out how it's balanced. Once 5 stacks of Miasma are up, it can really make life miserable. It's one of the few master difficulty daily events where I've had a level 59 character lose 1 vs 1 while I was using auto-battle. Even one stack of Miasma makes it hard to get off blockbusters on the treasure node. But at least there's a way to remove the Miasma, which feels a lot better than the nonsense going on with Robo-Fortune and Big Band.
(Robo-Fortune's is particularly terrible, since it also punishes you for using so many of her variants, particularly Blue Screened, so I don't think much is going to compare to that soon)