How are people doing so much damage when farming bosses? Some people outright instakill the bosses, and at times I feel like I'm doing less damage than a level 90.
My gear is:
>+51% weapon forge +6, smite
>head anima +6, clairvoyance
>everything else normal forge +6 enchants
>VHL class
My 2/3/4/5 skills do 9k/9k/5k/30-50k damage (if that means anything).
I try to use consumes like the potent battle elixir/felicitous philtre/power tonic/potion of speed/etc. but they don't really make much of a difference.

Also I get instakilled by a lot of bosses (like the hydra challenge or archfiend dragonlord). I know the clairvoyance helm makes you very squishy, but even if I take it off and switch to a tankier class (like AP), I still get instakilled and just can't solo the fight at all.