Unless you are blessing them, Wyrms are generally weak. As xdude said, I believe unstable gases would be more appropriate. This would mean however, that you would have to change your mark to fire to make them explode. It would make the deck more effective I believe though, and if you can afford the change, I would recommend it. If you cannot afford the change, then I would at least put in a shockwave or two, maybe taking out 1 Wyrm and one Thunderstorm. Thunderstorm is good and all, but its real uses only come out in a match against Malignant Cells or Skeletons. Shockwave is more effective at killing creatures, and can fend off the Otys trying to eat your Wyrms