Tonight's event was primarily for Su Yang to probe the situation on the Medicine Sect's side, and also to begin driving them out of the Capital City.
After the battle at the North Mountain Summit last time, the Medicine Sect surely wasn't going to swallow their pride and leave it at that. Upon their return, they would undoubtedly try every means to retaliate against Su Yang. But Su Yang had no intention of waiting for them to be fully prepared before making his move. He planned to drive the Medicine Sect out of Capital City first and then find a way to eliminate them completely.
Now that Ge Kaiyang's group had allied with the Medicine Sect, things had become slightly trickier. However, since it had already reached this point, there was no avoiding this confrontation.
Both groups had deep grudges against Su Yang. If Su Yang didn't act first, and they managed to gather enough strength, it would certainly spell his doom.