Less buttons to press. ;D
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Think about it. You need 50% irregardless so it's either two button for 50% charge then the 30% Def Down or 3 buttons for the charge and 30% Atk Up.
EDIT: I mean, if you want consistency due to having lower NP level, then take Waver. I don't need the consistency as much anyway.
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Oh, I'm sacrificing a slot for the Kaleidoscope. And that's why it works.