From the top of M. Sponda chairlift, take the blue "Delle Cime" piste that follows the ridge leads to the Mottolino gondola top station. Once below 2500 metres, you can decide to leave the piste wherever the skiing looks best and start heading down the open slopes of the Colombina. Keep descending, always drifting the skiers left. Once back in the valley and on the road you could either walk to the Trepalle chairlift or take the bus/taxi.