Try it on boss fights with high numbers (Fish of N’Zoth or maybe even Heroic Drek’Thar, although I haven’t tested it). But then again, the ridiculousness of Bwonsamdi has been suspected since his announcement — it’s just turned out to be even more than initially thought with elite or boss fights.
Well… No offence, but I think some self-criticism could help one improve a lot.
PS Yeah, I remember you and your difficulties and I know what I’m talking about. Reading what enemy abilities do, for instance, is definitely cheating and is utterly impossible without unbelievable luck (yeah, every time) and spending a lot of money.
Since I don’t like those folks, my recommendation would be the good old Xyrella, Velen and Anduin. Yep, these three can clear the whole (heroic) encounter without losses (unlike some other parties) easily, just don’t pick any stupid treasures that can mess it up.