Rogthoth used to be a normal Illithid. A creature born from evil thoughts and absolute control, but yet something a trained individual could take on. He is different. He became different. It all started with the Age of Darkness, the time the shadow dragon Zeoldoras aimed to rule the world and destroy all mortal beings. Living deep underground, far away from the surface and the damned sunlight, he encountered the dragon once, when his body was in the middle of being reborn through the power of it's god.
Rogthoth realized what was happening and with greed clouding his mind, he wanted to get some of the dragons power for himself. But he, who was just merely a creature worth of the shadow dragon's attention, was overwhelmed by the power of the unholy being before him. Flooded with the dragon's mind and thoughts and ambition, the creature that was just an Illithid became something more.
The mind controlling powers he possesses became far more powerful. Not even the undead could withstand his control. And as a servant of Zeoldoras himself, he was able to use part of his demonic shadow magic.
Now he lies in the ruins of an old civilization, waiting, preparing, for when his master will call upon him. Always eager and ready to build an army to aide him, to throw over the world that those pesky Gods of light try to uphold.