Om Namah Shivaya is so strong mainly because it includes At first the mantra, Om, that's the sound vibration of the beginning of generation. Then We now have namah शिव रूद्राष्टकम : नमामीशमीशान निर्वाण रूपं लिरिक्स शुद्धस्वरें गर्जति वेद चारी । तुजवीण शंभो मज कोण तारी ॥ २४ ॥ https://counting07260.blazingblog.com/20013898/the-smart-trick-of-bholenath-that-no-one-is-discussing