Rudra, Mahakala, or Rare Angon

Otherwise known as Mahakala, Rudra, the demonic son of Siwa and Uma, is born from the dalliance of Uma with a cowherd (rare angon), who was Siwa in disguise. Kala was born of the his spilt semen. This story is connected to exorcism of Kala, specifically on the day Tumpek Wayang.