Combining the name Twoface and Clayface wouldn't be so great if I ended up with Faceface... so Twoclay it is!
Harvey Karlo played an unstoppable knightly lawyer on tv, but as an actor he was tied up in crooked business that helped his stardom. When relations with the mob were getting bad, he got into an "accident" which disfigured half his body, ruining his acting career. Desperate to regain his fame he turned to an untested cosmetic substance to try and rebuild his image, but only ended up becoming a monster.
Not only did his body undergo a horrific change, his mind also became split. Half of him believed he was the heroic lawyer he played on tv, and the other half stayed as a revenge seeking victim. When the lawyer takes control, the clay half transforms and completes the other side of his face to perfection... but when the victim takes control, the clay expands and covers over the good side... showing a complete monster.