According to Chapter 10, what is the role of a Sadguru in a devotee's life, particularly in relation to karma and destiny?

As detailed in Chapter 10, the Sadguru plays a pivotal role in a devotee's life, transcending worldly limitations. The chapter states that by placing faith in the Guru's feet, he 'strikes a nail over the lines of destiny,' effectively changing one's fate. Pure service to the Sadguru is said to completely destroy the worldly existence (Samsara) and allows devotees to cross the three types of miseries. Furthermore, the text highlights the Guru's power over karma, noting that by his mere sight, a devotee's accumulated (Sanchit) and current (Kriyaman) karmas are destroyed, leading them toward liberation.