Moloch, the Exiled Archdevil

Cruel, prideful, and ambitious, Moloch is the former ruler of the sixth hell, Malbolge, who is currently exiled from his home realm. Millennia ago, he participated in a failed coup to overthrow Asmodeus for rulership of the Nine Hells. As punishment for his betrayal, Asmodeus stripped Moloch of his station and placed his daughter Glasya in charge of Malbolge]Malbolge. Moloch was then banished, but not before Asmodeus placed a great curse on him. Should he ever return to the Nine Hells, he will find himself transformed into a simple imp for as long as he remains there. Moloch now wanders the realms in search of any resources he can use to retake his throne, something he has tried and failed to accomplish on several occasions.
During the Reckoning, the failed coup against Asmodeus, his role in the plan was to hide an army of devils on Nexus that would serve as reinforcements in the battle to come. While there, Moloch learned of the Quintus Gems and believed that these artifacts could tip the scales in overthrowing in master. While his generals mustered his forces, Moloch went seeking the gems and began to hunt down the current gemholders one by one. Individually, they were no match for the archdevil as he slowly grew his collection of Quintus Gems, killing several gemholders in the process but leaving most broken and beaten to wallow in their defeat. Everything was going to plan until he found his final target, the holder of the Purple Gem. Knowing he could neither defeat Moloch nor surrender his gem, the gemholder took a third option and destroyed his gem before Moloch could claim it.
The gem's shattering released a massive wave of necromantic energy that killed the gemholder and knocked the gems Moloch he collected away from him as he was blown backwards. Unknown to Moloch, the surviving gemholders he had left alive had followed him determined to stop him with or without their gems, or die trying. In that moment Moloch was stunned, doing it *with* their gems was suddenly an option again. The adventurers reclaimed their stolen artifacts and were together able to slay Moloch on the Material Plane and send his soul back to the Nine Hells. As he felt his spirit slipping back towards his home, Moloch was confident the mortals had merely delayed his plans and that there was still time to claim the Quintus Gems before moving against Asmodeus. The moment he arrived back home, he learned that this assumption was very, very mistaken.
In Moloch's absence, his co-conspirators had been defeated and taken prisoner by the archdevils still loyal to Asmodeus. His own army had been found and set upon by Glasya's infernal forces, slaughtered on the Material Plane and sent back to the Nine Hells to face punishment. Moloch was stripped of his title and the power that came with it, as well as nearly all of his material possessions before being banished from the Nine Hells. Though it was still possible for him to enter the infernal realms, the moment he stepped foot there he would be transformed into a simple imp, a form he would retain until he left the Nine Hells behind once again. Ever since that day, Moloch has wandered the multiverse attempting desperately to regain the power and prestige he has long since lost, without any real modicum of true success.