What I have recently found when exploring the world is that sometines monsters got stuck in the poison cloud and eventually I cannot hit. In some even frustating cases, they chase me and keep on damaging my lovely FICSIT suit with no other thing to do than running out of the gas cloud. Then, surprisingly, I am able to git them again. In some lucky cases, they did not even realize I am out there, even when hitting with the basher. This is very annoying, specially when there is no space to scape from the gas cloud (cliff out there of course). Should be great to solve this in the upcoming patch.
