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Yes, thank you. I read it and just reread it several times. I experimented with the Shield of the Elements and came to the conclusion that it cannot deal damage higher than the actually received damage. That is, you cannot put the Shield of the Elements on a peasant, unleash 1000 archangels on him, and hope that the shield will destroy at least 10 archangels after the attack, since the peasant's health is only 1. I got damage higher than 30% of the actually received damage. I even got almost 100% on the difference between attack and defense.
But then I was watching a stream, and at one point, 400 earth elementals with the Fire Shield destroyed more than 1000 archangels, and now I don't understand anything about the Shield of the Elements. There, the theoretical damage from the archangels was 43K, the actual damage, taking into account health and the number of opponents, was 15K, and the retaliatory damage from the shield was 350K, 8 times more than the theoretical damage and 22 times more than the actual damage. That's why I'm looking for a formula, but I haven't found it yet.
Added after 1 hour 51 minutes
I think I figured it out. There, the opponent has an artificially inflated level, around 2500, and the Magic skill. Plus, the Sphere of Fire. According to the calculator, such numbers can be obtained, since the damage at such a level increases by approximately 19 times.