it is not possible to tank high-end monsters without parrying
when a monster does you 100+ damage within one second you loose a lot of stamina
also some monsters have high weapon skill so you may miss 2+ times in a raw
if a monster has high parry you can miss 20 times in a raw
you should also have enough mana to chain AI (some monsters use Mana Drain and so on)
and finally some monster has "anti-leach aura" making sampires absolutely useless