Which Shiva avatar is worshipped for removing obstacles and Pitru Dosh?

For removing obstacles and Pitru Dosh, Lord Shiva is primarily worshipped in three specific avatars: Mahakaleshwar (Time-devouring Shiva) at Ujjain is invoked for removing the karmic burden of unnatural deaths in the lineage and releasing trapped ancestral souls. The Mangal Dosh and Kaal Sarp Dosh pujas at Ujjain specifically target Pitru Dosh through Mahakaleshwar. Trimbakeshwar near Nashik is the most scripturally authoritative site for Narayan Bali and Nagbali pujas — both essential for Pitru Dosh Nivaran (ancestral curse remedy), especially for ancestors who died by snakebite, unnatural causes, or without proper cremation. The Skanda Purana explicitly prescribes Trimbakeshwar for these rituals. Kashi Vishwanath (Varanasi) is invoked for dying persons to receive Taraka Mantra directly from Shiva — a unique blessing that grants instant liberation. For ancestors trapped in preta-yoni (ghost state), the Pishach Mochan Kund near Kashi (associated with Shiva) is the prescribed spot for Pitru Dosh Nivaran. Devotees also chant the Rudrashtakam, Maha Mrityunjaya Mantra, and Shiva Tandava Stotram daily for general Pitru Dosh relief. Prayag Pandits can arrange specific Rudrabhishek and Pitru Dosh Nivaran pujas at any of these Shiva tirthas.