Well, I always had a hard time keeping up with block with my storm, but for ice it is a different story. My ice wizard has quite a bit of block with his gear, while he is maintaining decent stats. But ice is just built differently. If you really need block, I could suggest this item for you:
Teeth of the lords of night.
It has a nice 150 global block, and 25 critical chance global. That is for the level 90, atleast.
The downside to this item is the fact you need to buy crowns to attempt to get it from a card pack.