I tested it: 5 Psionicists, 15 Air Elementals, 10 Fire Elementals, 8 Earth Elementals, 2 Phoenixes, and a few Sprites are exchanged for 2 Angels: 5 Psionicists, 2-3 Air Elementals, 2-3 Fire Elementals, and 2 Angels remain. The hero has almost zero Piercing Attack: 3, 4, 1, 3, with a book, and I bought another one on day 111; it gave Haste, Slow, and an arrow. What is the approximate battle formation? Because in theory, it's clear that you need to gather 2-3 stacks of Phoenixes around the Earth Elementals or some other damage dealer, and then what? 5 Psionicists barely kill a quarter of a stack... And suddenly, I realized that Griffins peck at my Phoenixes in the first rounds. I also don't know how to deal with that.
well, that's assuming he didn't build up a huge army by week 2 :)