I disagree, her traps are insane but a lot of her utility comes with Polaris and her heals, which help out the most in the big boss fights her traps are ineffective in
Most of the late game bosses aren't huge, either; there's a few exceptions, but the overwheling majority of them are movable and iirc they all use status effects anyways, so Polaris and uhh that other move that increases magic defense is extremely useful. Counting chapter 6 onwards, I counted 13 movable bosses and 2 unmovable ones <_<
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KrahenProphet and Kana are on opposite ends of the Awesome Spectrum.