Another option would be to have it destroy up to two permanents but they have to be in the same stack. Thus, in many cases, it would simply be a more expensive explosion, but against decks with a bunch of SoG or SoV, you could destroy them two at a time. It could also be used as a mini-earthquake in that case. It would also destroy 2 bone walls if you wanted to do that.
One other thing you could do if you think it needs nerfing (either my version or laxa's) is to require a sacrifice, immolation-style, of a nonquantum permanent.