Gearing help for my Nova sorc

I been leveling up my novasorc for a while now, (fml) And I am now ready to start gearing up for maps, the keywords for the build is health, block and faster cast high damage, anyone know of some "must have" items ? so i can get rares aroudn the key items?

I started out thinking crit, but now im leaning towards cast speed and cold gem to freeze mobs when they get in the shock nova