Pradosham is the time present between one and half hour before and after the sun set (One muhurtham). Pradosham is a combination of two words pra and dosham in which Pra means Removes, and Dosham means sins that is the time that removes sins. This Muhurtham comes every day, however, the Pradosham time on triodasi day is considered very auspicious. That too on the Krishnapaksha triodasi (that falls on dark fortnight or triodasi before Amavasya). If the Pradosham falls on a Saturday then it is referred as Shani Pradosham, which is considered even more auspicious and this time has immense importance in the Shaivite tradition.
As per the karanagama, worshiping God Shiva along with God Rishabha or Nandi during the pradosha time or pradosha pooja will get immense benefits. It is believed to relieve their diseases and mental disbalances, fears of death. It is also believed that the devotees will be uplifted from poverty by the gods mercy along with fulfilling all their wishes. If a praosham day falls on a triodasi which is a Saturday, then it is referred as Shani Pradosham. As discussed in the story that God shiva saved the worlds from halahala on a triodasi which was a Saturday, thus the shani triodasi day got immense importance.