Shauri's Sonorous Clouding ( Bard invis)
 

If you're playing this song and it breaks (click it off, interact with something) and subsequently reapplies itself, you won't actually be invisible to mobs. You'll still have the buff icon, but they will con like they would otherwise and will definitely attack you if aggressive.

If this is already know, sorry for wasting your time!

Re:
 

Try it out, I was able to re-create it repeatedly while I was trying to bank in Neriak.