After trying all sorts of fancy stuff with a group at one end of the courtyard on the same Sarnaks, we called it a night. The next morning my ranger went to the other side to a duo of Sarnaks, boofed one against wall, boofed the other the other direction, did a hail, said help, and got update. I did NOT have a buff from the Stupefying Sarnak Pheromones from the night before.
One warning is if you try to exit the courtyard to the rest of the zone with that potion on you, they will see thru your invis and kill you. However you will get a update for going thru the gate.