Analyzing a two-player game isn't interesting, but I did some testing with the three-player scenario.
The army composition, as specified in the task, is: 5 Psycic, 10 Fire, 8 Earth, 15 Air, and 1 Butterfly.
I used a hero with 6-6-3-2 stats and expert offense, and the only spell needed is Bless.
Wow, I never would have thought it could be done this way; I respect Wicc even more now.