The Xenos technology uncovered by the Adeptus Mechanicus on Orvan IV was originally harnessed by the explorators to create an armoured walker, the Inceptum. The artifact housed an unprecedented amount of power compared to its size. Tech Priests were even able to mount weapons of the same magnitude to those found on great Warhound Titans.
Although the new found technology promised countless new technological innovations, at the time the entire sector was in turmoil, ravaged by an Ork Waaaagh!. The project was scrapped and the ancient war engine forgotten onto the planet. Although several teams were dispatched to recover the artifact, they never returned from their missions.
A millenium later, the Adeptus Mechanicus have returned to the planet to recover the Inceptum, as the entire sector is once again at war, this time with the newly emerging Necrons of the Salau-Tek dynasty. Upon arrival, the expedition forces found the research facility destroyed and the relic stolen. The Inceptum was recovered by the reawakening Necrons of the fringe world, and eventually converted to the "true machine god". The Imperial forces believe that the Inceptum holds the key to defeating this new threat. The artifact is the only record of the research carried out on that alien technology, and it perhaps holds the secret to defeating it. If all else fails, the Imperium hopes they can harness these powers once again and turn the Xenos technology against themselves.
Now the gothic war engine marches alongside the legions of Orvan IV, wreaking havoc to those forces that once created it.
This is the awesome model that we all got in our swag bags at Adepticon 2012. I decided to integrate it into my Necron army. I didn't want to go and modify a one off model like that, but I'm still planning on playing it as a destroyer lord (or a second c'tan shard).