Yesterday my team tried to take a short cut to a good xp spot in the hole by jumping down. We arrived in the litte area near the Guardian but the exit was locked. A pile of rocks forms a door but clicking on them just got us the - "you don't hold the right key in your hand" message. We tried the and the to no avail. I did some research and couldn't find anything. Does anyone know where to find the key to that door? Or did we overlook something really obvious?
PS: There are no tiny holes in that door to wiggle thru

We considered to get summoned by the mobs on the other side but couldn't come up with a consistant way of getting 3 people summoned one by one without getting killed - these gargoyles are not trivial to my team.