Complex sentence: Foamy proceeds to warn her, stating that all of her gained knowledge, enlightenment, and realizations over last ten years will also be done away with or subconciously suppressed-all she'll be left with is a faint feeling of déjà vu.
Split into simpler sentences: Foamy proceeds to warn her, stating that all the gained knowledge, enlightenment, and realizations from the last ten years will also be done away with. That all she will be left with is a faint feeling of déjà vu.