Shalya

In the epic Mahabharata, King Shalya (Sanskrit: शल्‍य) was the brother of Madri (mother of Nakula and Sahadeva), as well as the ruler of the kingdom of Madra (Madra-desa). Shalya, being a skilled archer,a powerful mace fighter and formidable warrior, was tricked by Duryodana to fight the war on the side of the Kauravas. Shalya had a strange ability which made him invincible in battle. The more aggression his enemies showed while fighting against him, Shalya would become even more powerful thus making him victorious. Only Yudhishthira could kill the powerful warrior because the eldest Pandava was not a man of aggression. Thus instead of becoming powerful, Shalya was severely weakened and Yudhishthira could easily slay him.