I realize this is a rather significant alteration of the card, but I'll preface it by saying that I was fully expecting a card named Avalanche to be in Earth.
-same cost (but earth quanta)
-deal 3 damage to all creaures
-delay all survivors for a time (however many rounds is balanced)
Alternately, simply changing the name would set my mind at ease :p Something like tidal wave or blizzard or arctic storm or katabatic wind (there's a good one for you; wiki that
though that could conceivably go with air as easily as water)
I think this is quite a powerful card, actually, but the cost is very high. Freezing ALL creatures in one shot, though, is worth a lot, as it is a game-changing effect. In its current form, I'd still find room for one or two copies in my 60 card timebow stalls instead of permafrost shields, and go with something else for a shield.