First of all sorry for my english not my first language.

So I've noticed that if you attack out of stealth using an ability and you kill the target, then all enemies around that target will not register your presence. You can then proceed to damage them even not being stealthed and they do nothing.The good example are the skeletons in the Sea Cave because they easily oneshoted. 
 

It's worse than that -- you can actually one shot things you shouldn't be able too -- see https://forums.obsidian.net/topic/108177-auto-kills-out-stealth/

Sneack -- it's like a portmanteau of sneak snack. I like it. 

Yes, running into this now.

 

I just 1 shotted a whole group of enemies and they never initiated combat.

Hey everyone!

 

Thank you for the heads-up on the sneak attack issue.  We should have a fix lined up that is being verified to make sure everything checks out.  Keep an eye out for patch notes to see when this is implemented into the game.  If you notice the issue is still present, please let us know so we can take another look at the issue and get it resolved.

 

Thanks for the help everyone!