The Pilot was repositioning 12 passengers from the bottom to the top of the Ghosts Drimie ski run. Upon departure, the Pilot elected to take-off downhill and downwind due to the terrain. The aircraft started to settle as it transited across a field and entered a ‘snowball’ at which time the pilot lost visual reference. The main rotor blades struck a tree and the helicopter touched down in the snow, remaining upright. There was substantial damage to the helicopter but there were no injuries.