"Hard" dungeons in DF were

Haukke HM (minilvl last boss pure DPS check)
Sasti HM funnily could wipe all bosses easily
Amdapor HM (Demon Wall part but after a wipe didnt fully reset iirc)

Most dungeons are designed to be farmable without wipes though it is sad but on other hand for challenge we have raids and primals

I prefer anyway dungeons with story... like Tamtam HM <3