When fighting monsters - watch yourself less you become monstrous.
When fighting monsters - watch yourself and arm yourself with truth.
When fighting monsters - watch yourself and shield your deep innocence.
When fighting monsters (and you must fight your monsters no matter the depth of the abyss) - watch yourself and let your whole self stand.
"Whoever fights monsters should see to it that in the process he does not become a monster. And if you gaze long enough into an abyss, the abyss will gaze back into you." Friedrich Nietzsche