I think they fixed the 8,7 M boss already - Now 8.7M boss now only start to come for players who killed 100+ bosses.
In begining 8,7 M boss starteded already after 60 kills. I dont know I they are goint to change the 8,7 M boss anymore than that.
Ofcause players who kill 200+ bosses get the 8,7M boss almost every time.
Imo the 8.7 M boss is really anoying.