I was about to open my own topic regarding current stealth
(just finished the demo with a single lvl 5 toon exploiting stealth).
I think the problem is the poor AI towards sneaking/ invis.
AI obviously freezes upon being invisible. Only performing basic actions such as buff yourself, or move out of unfavourable ground.
I hope this is only an alpha bug D:
if the AI would simply turn towards your last seen position or attempt to chase then random search, things would be much, much harder already.
Contaminate etc are such great stealth counters - yet AI never uses it if you are hidden. This clearly needs change and I'm quite optimistic it will be adressed eventually.
additinally during party play - for the upcoming content I believe a "hunter Ai", that specifically tries to destealth, hunt and kill those who try to hide would be a reasonable addition to some enemies
