As per Shastra’s :

।। ॐ पशुनामपतिम् परेशं गजेन्द्रस्य कृतिम वासनाम वरेण्यम ॐ श्री महापशुपतये नमः ।।
We bow down to Pashupatinath the destroyer of animal instincts and the protector of humanity.

Essence of Fifteen Mukhi Rudraksha:

This is a unique and powerful form of Lord Shiva. Pashu refers to all living creatures but it also refers to the animalistic nature or baser instincts of human beings. As Pashupatinath; Lord Is the God of all creatures. Worshiping him establishes a deep connection to all forms of creation and also helps humans evolve to higher levels of spiritual evolution. The 15 Mukhi Rudraksha is similar in its traits to the 14 Mukhi Rudraksha. It has all the divine powers of the Devamani with additional powers that help in procurement of wealth with good fortune. It is a divine bead of good luck. It enhances visualisation skills, aids decision making and attracts good prospects to those who wear this lucky talisman. Sanskrit texts invoke the power of Lord Pashupatinath by these lines from the popular Shiva Stotram!