I remember a boss or two that when they were released were not intended to be a gating mechanic but were mistuned such that they were physically impossible to beat in current gear at the time. Unfortunately my google-fu is weak today and I'm getting nothing. anyone reacll which boss(es) it was and which guild(s) proved it? A link to the proof would be even better.
This would've been back in Wrath or TBC. I think.