Guild Wars 2

on stealthing, I get an icon with no description, just a little square where information would go if that field was filled in.
I can’t quite make out what it is, but it’s a huge fat black border, then a little bit of red in center.

Placeholder?

I’m pretty sure it’s just a bug.

Was it this icon? http://wiki.guildwars.com/wiki/File:Invulnerability.jpg

Image on the right

Hidden Kill trait in the Critical Strikes line grants its 100% crit chance while stealthed via a buff with the icon Kaizer linked.