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I tried it. I used a Moner build with 4-2-1-3 experience, offense, 12 air units, 58 butterflies, and the rest from the castle, up to the Psychos, without a book (there was nothing useful in the guild). Only 2 birds die.
They really like to kill air units immediately; even 5 Orcs couldn't distract them. I didn't try to come up with anything special because the difference between levels 2 and 6 is too big.
I concluded that it's not possible to win with a standard build and without serious magic. But bonuses can vary, so it depends on the situation.