shadow warrior(haven't tried this with any other character yet)
high hit point regeneration
grim resilience(optional, but nice to have on you)
in the forrest right out side of Grunwald Cave Dragon location, there are human mobs that summon elementals that will attack you. keep reflective emenation up, and make sure your health is regenerating too fast for the elementals to do any real damage. stand in the middle of a crowd of these human summoners, and just let the elementals attack while RE mows them down. any additional mobs will be killed by RE, discovered this doing a solo boss run on the dragon in gold difficulty. the summoners will not attack you themselves, but will keep summoning elementals.
with my normal equipment on and stats, I have 4040 armor, 6.2k hp, and 132/s hit point regeneration. at level 50 in gold difficulty these mobs do not budge my health one bit.