Yay, MMC is making cards too!
Anyways, this card is rather UP.
Compare to another mass AoE card like Thunderstorm.
Sure, it doesn't hit burrowed creatures, but honestly, burrowed creatures can only really come from a few elements (Earth, Darkness, and sometimes Entropy with mutations).
I'd say to lower the cost a bit, especially on the unupped. Since it hits your side as well, you could probably lower it to 3
, maybe even 2
and still be fine.
EDIT: Discord replied while I was typing.
MMC was smart here and chose not to make it Earth for a reason.
If it were Earth, then you would likely be hitting your own burrowed creatures for 4 damage rather than the opponent's since Earth has the most burrowing creatures (with Graboid and Shrieker being the most used).