I took a few tests related to damage. I chose slimes since I have the best gear for them. I am not necessarily saying this is viable, but I'm saying it can be done. All of these screenshots were taken in Elite mode.
Armor 1
Armor 2
Polyp 1
Polyp 2
Colony 1
Colony 2
Baby Lichen
I do have faith in armor. I believe that you can possibly tank, even in T3. It's just hard to do against, say, Shadow enemies because all shadow armor has some status resist or something, which lowers the vanilla shadow resist.
what about strength in unity?