This cursed "treasure" can be seen in a concept art sketch when it was carried off by an owl named Herald before being returned to the hands of the Oni Moloch. It is the second to last relic to collect in Konquest, being found in the Edenian Ruins.
In Mortal Kombat: Armageddon, it doesn't seem that Moloch possesses it, but it appears during his Versus Render, and during some of his special moves. It was featured as one of the collectible Relics under the name "Moloch's Ball" found within the game's Konquest mode as well.
Moloch with his chained Giant Ball of Death.
Moloch's Ball in Konquest.
Moloch as he is seen with his Orb.
The Giant Ball of Death, also known as the Mystical Orb.