This............ Sounds like Sky/Sea Gods in FFXI (Last expansion I played was WoTG) but I heard that since then some HNMs that was back in my day was able to be forced spawn or something like that but that's about the same thing, only difference is that other players are able to help out if they feel like it.

Don't forget to address the whole if "this" party wipes to that NM can "these guys" take it? In the case similar to Sky/Sea gods they shouldn't be able to.

I can't really see people helping also unless they just want to out of kicks and giggles and not get anything for it and using up 5-15 minutes of their time.

POST IS TOO LONG BRB.