Golden Fury NiM
Don't know if u want to list that boss but i will post it anyway.
We got the hardmode achievement while we did nightmare mode. I have no clue if there are different hard and nightmare modes or if it's the same and just buggy.
PS: Pls rank up ambassadors by subtract 2 hours from their displayed achievement time. They play on our server and we know that none of the guilds from our server will, which are listed here, cheat on the boss reports.