I use it a lot in PVP, but not against my target. Fire it on somebody unsuspecting or further out from your group and it causes them to have a bit of paranoia, and I tend to find people react differently because they're hunkering down waiting for poison arrows to start raining down. Once the Mark flags people tend to look around quickly to look for threats, buying you a few seconds (which may be all that matters).i dont use it. not in PvP anyways. your targets can see the mark above them, which basically tells them to start stacking shields and purging like crazy. not to mention its a double edged sword. if you can hit your target before they block/stack damage shields, you may just get them. you can also use it at range.... but up close assassinations? no. i dont advise it.