- Walk up to a mob we’ll call Mob #1. Sap it.
- Interact with something (in this case, Zanj’ir Armaments for the Terrace Terrors WQ).
- Go into combat mode, even with Mob #1 sapped. (Standard behavior.)
- Vanish.
- Stealth a few yards away and mount.
- Fly up. The bodyguard flies up, too.
- Fly back down to another safe spot, not close enough to aggro Mob #1.
- As soon as the sap times out, suddenly go into combat – even while stealthed – and watch as Mob #1 comes charging at you from well outside aggro distance.
tl;dr: Rogue Vanish needs to drop aggro from bodyguards as well as the rogue.