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Immortal Souls, FWIW, now that I finally finished the write up. Seems like this sort of mechanic should be a trope somehow. Barrier Change Boss is close, but that requires the barrier to, well, change...
In my opinion, it would just be a specific kind of Elemental Rock–Paper–Scissors, perhaps an inversion or Played With example. It still involves elemental alignments of attacks and defenses that need to be played strategically against each other.
"Pale Ebenezer thought it wrong to fight, but Roaring Bill (who killed him) thought it right." - Hillaire Belloc, The Pacifist

Is there a trope that's basically an inversion of Elemental Rock–Paper–Scissors? Like, each enemy has a certain attack type of armor, but you're supposed to use the matching attack for that armor, not the opposite attack?
For example, if an enemy has armor protection colored blue, it means you have to use the blue Melee attack to break it.