The origins of these priests' master teachers explained as they've once believed that the long lost, true Emperor of Outworld was a bringer of order and civility since Onaga was a powerful military commander which already made their home of Outworld into both a unified, perfect realm and a majestic civilization for thousands of years long before he was betrayed and poisoned by his former advisor Shao Kahn who then stole his throne from him. The Lava Shrine Priests are the polar opposite of the Shadow Priests, royal servants of their king's betrayer and sworn enemy Shao Kahn.