This was formerly the access quest for the inner temple of the Silent City, called The Fountain of Life. It is no longer necessary to complete this quest to gain access to The Fountain of Life as of LU48.
There are 3 versions of this quest, each picked up randomly when you inspect the Stone Tablet. The only difference between versions is the order in which the monoliths are inspected.
Warning: You will zone-in within aggro range of multiple (4) 62^^^ Heroic gnolls, so be prepared to fight. There is also a patrol of 3 more (Heroic) gnolls that goes as far as the entrance.
Turn around, open the door and enter the foyer.
Since the access quest was removed, you no longer need to place any runes into the sockets on the floor, the quest completes immediately. Although the sockets remain active, interacting will tell you that you don't seem to have any runes to fit into the puzzle.