Abusing The Curse
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I had realized that the Frost Queen had smartly created this challenge so it wouldn't be easily cheesed by long ranged magicians that could cover wide ranges. She granted the soldiers that appear here to invade the orb equipment and buffs that boost their resistance to long-ranged magic spells through the roof, while keeping them normal in everything else.
This means that they can actually receive pretty substantial damage from point blank attacks. Physical attacks that combine magic are also okay, and apparently Benladann's breath attack not pulverizing them as it should had been because of their resistance to long-ranged magic attacks, which dragon breath are at the end. However, when she approached them while enchanting her body and weapons with her Chaos Aura, she was able to easily kill them after weakening them with her breath attack.