Liriel

Known only by her first name, Liriel is a hired mercenary. Contracted by the Emerald Enclave, she is on a direct mission to retrieve the Puzzle Box for safekeeping. The high council of Druids and Fey Priests of the Enclave have received omens that the Puzzle Box's mere existence will tip the balance of power in the area. The visions were clear and strong enough they felt they needed to be proactive in this task.
Liriel's training as an assassin and bounty hunter gives her the stealth and intelligence gathering required for such a delicate mission.
In exchange for the Puzzle Box, Liriel has been given a token of the Emerald Enclave to trade for the item. The Amulet of the Beast Whisperer. Liriel's orders are to retreive the box, keep it safe, and return it to the forest empire where it is to be held under watch by the Enclave's high council.
Update: On 19 Kythorn 1491 DR, Liriel appeared at the Ashen Sanctum to assist in dispatching two of the remaining The Redbrand archers. But the Owl Friends, led by keen investigation by Sparky BaneDusk, discovered that Liriel was actually the Black Spider. She quickly cast the Teleport spell to blink out of that location. She's waiting now to confront the party at the Wave Echo Cave.