Frozen Ice Chest
Inside you are guaranteed to find from 800 to 1200 crystals Sidian.
Also, when you open a chest between December 1 to March 1, with significant probability, you can get Lericon Summoning Rod.
With a lot of luck inside the chest, you can find a class necklace orange quality from the set of Shadows for characters at levels 68 and 88.
Use the chest to start defrosting it. You cannot defrost more than 1 such chest at a time! Can only be purchased during New Years Sale.