I just got Reaving Wind the other night. Here's a quint tip for anyone still needing it.
Camp in the Glacier @ I-9 just past the Ruzors (off to the left side as you were going to Fei'yin). I was able to get myself wedged inbetween some rocks during the fight. It helped when the Amp would spam its knockback.
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Frigian
Blu Brd Dnc Pld Bst Rng LVL 90
"If you immediately know the candle light is fire, then the meal was cooked long ago."