Bus de Tofana is one of the most popular lines in Cortina d'Ampezzo and is very famous in the Dolomites. After a walk with skis on your backpack, which takes about 30 minutes from the top of the chairlift, you'll get into a short but technical section. There is a steel wire where you'll scrabble down to the rocky arch (rope and crampons are sometimes useful, a 30 metre rope will be plenty). You are now on the sunny side of the mountain - get your skis on and enjoy a beautiful wide couloir, skiing next to steep yellow rock walls. In the middle of the run move to the right (facing down) and ski under the amazing south face of Tofana di Rozes Pillar, it is very famous for its fantastic climbs. In the last part, you'll follow the wires of the supply cable car of Rifugio Giussani and get into the summer trail to the Rifugio Dibona. From here follow the road, usually groomed, that leads to the ski slopes and you'll easily reach the lifts to Socrepes or Pié Tofana.
This is definitely a must-do descent, be careful to choose the right time to ski it, as it faces south and the first steep part of the descent needs the snow to be softened by the sun. There might be some rocks sticking out when the snow cover is not very good.