Answer: diabolic

AnswerCrossword Clue
DIABOLICOutrageously wicked
DIABOLICRather wicked
DIABOLICDevilish
DIABOLICFiendish
DIABOLICBefitting Beelzebub
DIABOLICInfernal.
DIABOLICEvil.
DIABOLICFiendish.
diabolicdevilish (fiendish (devilishly cruel))