Yes, I get killed by these thieves too.
Yes, this never should have left beta.
No, ANet doesn’t care, or won’t do anything for a while.
Yes, I have made a thief myself now and am leveling it, because why put an effort for kills when you can just 1-2-3 kill someone in 2sec? And even if you fail you can disappear for good in perma stealth and come back whenever you want it.
Fun fact: when I made my thief, ALL the people in Tutorial area were thieves except one person.
Thieves.
As Sebyos said, they are beyond annoying to fight against. If they don’t instagib me, they will just stealth stealth stealth, if that doesn’t work for them they will run away and there’s nothing you can do about it. They are invisible insta-kill class that can also escape without punishment because you can’t catch them.