I've been tackling Pantheon of Hallownest but Nightmare Grimm fucks my ass every time I get to him. I shudder to think what it would be like to do this shit with bindings, not that my casual ass will ever try it. That being said, triple mantis lords fight was probaby my overall favorite in the game, it's really satisfying to dance around and poke them as they constantly come at you from every side.