Synonyms of malevolently

3 Syllables
falsely, malignly, crookedly, fiercely, basely, disloyally, faithlessly, roguishly
4 Syllables
frighteningly, tigerishly, maliciously, dishonestly, perfidiously, traitorously, treacherously, unfaithfully
5 Syllables
maleficiently, dishonorably, falseheartedly, unscrupulously, underhandedly