Goblin Shaman resistance lowering stacks and does not appear to have a cap. e.g. it can go negative.
I'm not sure if you can go beyond -100% with it.
But, you can definitely go negative. Very handy for wrecking those bigger stacks.
I was able to beat some heavily armored Hu-Mans by using Ghost Sword to lower existing physical resistance, then goblin shaman would slowly bring them to like -5%.
