Just got out of of an icc and while doing Lord Marrowgar, I noticed that I couldn't get hit by blade storm as long as I was standing in a certain spot in his room.
Sadly the only pic I could take was this one.
Basically behind me is going to be blocked by an ice wall, but if you run into the wall, you can get slightly behind the ice. That's where I wasn't taking any damage.
Someone will probally have to test this again just incase i'm retarded or somthing.