I had earlier daily task to kill Lizardman Shamans. Before the patch where Shayzien armor was added to the game, Shamans did all the attack patterns correctly. However earlier today when i went to kill them, they only spammed the Acid attack. Afterwards to confirm i killed around 10 more of them and they still kept spamming it. Meaning that with the Shayzien armor on, you are able to just stand still and semi- AFK kill them without having to worry about taking even a single damage.
Assuming they weren't intentionally made so that they deal no damage at all with Shayzien armor on, this must be a bug.