Sounds like OP has a choice to make:
- Screen every player to ensure they are worse than themselves so the fights feel meaningful
- Forgo some loot so that the fight can feel meanignful solo
- Accept that someone will always be blasting
Not much in the way of other options. And i hate the group play incentive, but its the price i pay to be able to maintain my own pace and not deal with others while i do whatever. Either the group play justifies the loot or its not worth the feeling of inadequate contribution. Either way, these are problems the OP can fix by going solo or turning off crossplay 