I hesitate to put "suggestion" in the title, since I'm well aware this could be a terrible idea. It's just surprising to me that there's a firestorm card but no blizzard card. Something like 2 damage, encumber 1, duration 1 (or 2) to all players.
Encumber without line of sight? Yes please! But only if I am the only one allowed to use it. Seriously though with positioning being such an important aspect of this anything that allows you to ignore it has to be very carefully balanced. I don't see how this could work. I suppose like firestorm your guys are being hit by it as well but if you put it in your deck you probably ways to counter it as well.