Exhausting running a severe distance of 42 km (General) or 20 km (Warrior) with a total ascend of 1500 / 850 meters, maintaining high-speed pace with no time to rest. Long climbs, tiring descends, difficult winter conditions and icy air. To succeed with the additional challenges and obstacles and finish the run in the allowed time, one must spare no effort and forget the words „fatigue“ and „pain“.