After bathing himself in the unique protoplasm of an underground pool, Clayface could transform himself into any shape his mind could concieve, with Amazing ability, or about 48 hours. If he is limited to his synthesized protoplasm, his ability is only Typical, or about 6 hours. Any form he assumes is still limited to the material strength of the human body.
SCUBA Diving * Biochemistry * Treasure Appraising
The Secret Society of Super-Villains
While searching for sunken treasure Matt Hagen discovered an underground grotto that contained a glowing rainbow-colored pool filled with a bizarre form of protoplasm. Slipping into the pool, Hagen emerged to find his skin had changed to a hard clay-like consistency. With effort, Hagen discovered he could restore his now-pliable skin to its normal appearance or transform his body into any form he could imagine, from a centaur to a buzzsaw, for example. With this newfound power, Hagen -- now calling himself Clayface -- embarked upon a series of daring robberies that led to his capture by the Batman, who ultimately uncovered Clayface's hidden grotto and apparently destroyed it. However, Hagen had hidden a supply of the glowing protoplasm before-hand and, escaping from prison once more, synthesized it, regaining his shape-shifting powers. Repeated use of the synthetic protoplasm ultimately took its toll on Hagen's body, forcing him to seek a new path to his underground grotto, where he discovered his original rainbow pool had not been destroyed after all.
Restoring his powers, Hagen lured Batman and Superman to his grotto, where Superman used his heat vision to evaporate the pool completely.
Now left only with synthetic protoplasm, Hagen has chosen to remain in prison until he can find a way to overcome the protoplasm's dangerous side effects.