Where is the soothsayer in the castle in winter?

Underground, there are several entrances, one in the corner of the front yard of Dongbao College. One is in the dormitory. Go underground and follow the bloody road, kill a skeleton, follow a road, and then see an altar, where you can summon the flame monster. Keep walking and pay attention to a closed door, which is Master Zhan. Try the magic of showing the path. Never used it before. It might be useful.