This is the first time I made it to the Silver II league and had a chance to open 15 reward chests at the end of the season. I will never know if I would get it also if I stayed in Silver III, but there was one Legendary card: Djinn Oshannus! With the Void ability and a plenty of life, it is a great tank against magic attacks. The 500 extra Power also puts me closer to Silver I, although it's quite far away. Nothing special apart from that though, a few cheap common cards, potions and a negligible amount of DEC.
Good luck to everyone with the end-of-season drops and see you at the battlefield ;)