mephistophelian (adjective)

1. In the dark forest, the mephistophelian sorcerer cast wicked spells to gain control over the kingdom.

2. The mischievous imp played a mephistophelian prank on his friend by turning his hair green overnight.

3. The villainous character in the cartoon wore a mephistophelian grin as he plotted his dastardly schemes.

4. In Greek mythology, Hades had a mephistophelian demeanor as the ruler of the underworld.