I would replace one of the Fallen Druids with an improved mutation, since to use the Fallen Druid's ability you need to draw one of 3 supernovas. And even then you run the risk of the druid being killed the turn after using it, and with one supernova you'd only be able to use the ability twice anyway.
Other than that, looks pretty fun .
Edit: Just recounted the improved mutations, and you have 6 already. Maybe take another supernova instead of the fallen druid to fuel abilities more? Or a dissapation shield unupped? Or just keep it as is; it probably doesn't matter .
Yep, you are right. Whether to have 3 or 4 Supernovas is a good question. Believe it or not but this was the last thing I considered before taking the screenshot, and I'm not 100% sure which one is better. I took 3 because I figured out that I still need to get that 5 quantum before I can play the Elf, so I don't need that Life quantum to pay for his ability early on.
Also what kind of Mutants you get affects on how many Supernovas you need. It sucks when you get a good ability but cannot afford to pay for it.
I took 3 Fallen Druids because I always take 3 copies of a card that I would like to have relatively early in the game. It could work with 2 (I did have 2 at some point of testing) but then you would see it less frequently in your opening hand. Then again it's not like it's a crucial card in this deck so who knows?
If anyone has time and energy to test this out, try it with different numbers of Supernovas and Elves, and tell me which works the best.