I had an idea of doing that, but 7 days is not enough time to make combinations, as making the towers took me a lot already.
Something I forgot to mention in-game because of time, is that the main hitters are fire, nature, and electric. while wind, water, and earth are more on the support side.
the main strategy is to put them all together since alone towers do almost no damage, but I had some trouble with the numbers in the first waves(not enough playtest).
If you see the video on the game page, it shows a viable solution.