Answer: diabolic

AnswerCrossword Clue
DIABOLIC

Outrageously wicked

DIABOLIC

Rather wicked

DIABOLIC

Devilish

DIABOLIC
Fiendish
DIABOLIC
Befitting Beelzebub
DIABOLICInfernal.
DIABOLICEvil.
DIABOLICFiendish.