Karnataka votes on May 10 - and a state that is famous for its revolving-door politics is seeing its fiercest battle yet between the BJP and the Congress. While BJP is facing multiple challenges in the form of anti-incumbency, corruption allegations and desertions of disgruntled leaders, the Congress hopes to ride the wave of BJP's shortcomings to victory. Who will win the battle of Karnataka. NDTV'S TM Veeraraghav decodes.