All of those cards are very strong before nerf. Howler Golem, Firewall, Arcane Sphere are pretty cool neutral cards. Some of the other elements looks strong too but right now I could only imagine since I used nature deck only so far. I wish I have the opportunity to try some other elements beside nature to understand them better.

My scholar manager said he will rearrange deck to the stronger one after some weeks

Great post about the GU Update, Kstreet, love it