The Reclaimed Treasure of the Emperor decoration can be dropped from Stalwart Leader Command Packs, which were released on the Cartel Market and bought with Cartel Coins. Cartel Packs, including the Stalwart Leader Command Pack, include a random selection of items from the Stalwart Leader Command collection of items. You aren't guaranteed to get a Reclaimed Treasure of the Emperor decoration from a Stalwart Leader Command Pack, but it is one of the few ways to get a Reclaimed Treasure of the Emperor deco apart from buying it on the GTN from another player.
If you're looking to get a Reclaimed Treasure of the Emperor, the easiest way to get it is to head to the Galactic Trade Network (GTN) in SWTOR and buy it with credits from another player. If it's very rare and not available on the Cartel Market, you could try buying from the GTN and hope you get it.
Requirements to Unlock
Have completed Chapter XII “Visions in the Dark”
Have completed the first mission for Dr. Oggurobb to recruit Talos Drellik (thanks to Derzelaz for the update)
Interract with the mission alert and travel to Yavin 4
Enter the Architect’s Hollow Cave while searching for the Sith Artifact (it will be marked on your map)
Inside the cave you will find Harris’ body remains. Examine it and you will find the medallion
In the newly appeared toolbar you will have the sith medallion available. Activate it in the spot, shown in the screenshot to summon a monster. Kill the monster and loot the Crystal. Open your inventory and click to add it to the medallion
Go back outside the cave and turn left. You will notice a “box” sitting on a pedestal. Click it, defeat the Massassi and loot the Tablet of Victory
Go back into the cave and click on the Artifact
Following the Sith Code, you have to insert the tablets you have in this order:
After placing the tablets, touch the Artefact with the medallion and you will be teleported into the Hidden Hollow. There you will find a Dashade named Ak’ghal Usar. It may look like Khem Val, but no. If it was released on 1st April, it could have passed for a nice SWTOR April Fool’s joke :)
You have an option to recruit him (Dark Side) or reject him (Light Side). In the video I choose the Light Side option.
If you like to, you can check my full unedited video of me doing the quest. It was live streamed exclusively for my Patreon supporters and I never intend to publish it in its raw form. However, the video linked in the beginning of the guide is edited version of the full stream archive.
Most Honorable Commander,
I write to you under dire circumstances--please forgive me for not forwarding this request via proper channels. I have received word that my research team on Yavin 4 has suffered crippling losses while continuing the investigation that you and I pursued on that very same moon. I am currently engaged in a critical assignment on Manaan and cannot investigate the situation myself.
If there is any chance that you yourself could look into the matter and complete the team's work, Doctor Oggurrob and I would be forever grateful. They were close to a significant breakthrough, I'm sure of it. You could finally shine a light onto a mystery that has remained unsolved for centuries!