Ghoston is a teenage ghoul chained to a heavy iron spiked ball. Formerly a human, after pranking the wrong sorcerer, Ghoston was transformed into a ghoul and chained to a ball. Later, after absorbing the Ghost God's Crystal, Ghoston got the ability to create little exploding ghosts to launch at his enemies, as well as the ability to teleport. 

Ghoston has the personality of a stereotypical high school bully, with the obsession of living a large and luxurious life. He's also a bit of a prankster. He's a narcissist who took pride in his formerly good looks and holds scorn against the sorcerer who turned him into an ugly ghoul. 

For a reference voice, use the english dub of Katsuki Bakugo from My Hero Academia.