mostly just champions and elites that are immune.
the oblivion knights / abyss knights or whatever they are called and venom lords in a4 seem to have high stun resist and it doesn't always work.
i haven't really played around in a5 much other than the progression to kill baal, so i'm not sure about monsters in wsk

the raven lore + earth shifter are items I want for a silly druid buil:) your barb is a more geared version of my singer/zerk hybrid. I want to make a strong 2h sword for my barb like death CS kuz he doesnt do the shield thing

This page: https://www.theamazonbasin.com/wiki/index.php?title=Stun_length explains it pretty well.

War Cry can be blocked: https://www.theamazonbasin.com/wiki/index.php?title=Block#Monster
Doom Knight features in the 2nd table.

still waiting on stormshield though and a better maras / highlords + gores