{Meanwhile|In the meantime|At the same time|During this period}, hidden {completely|entirely|} from the {watchful eyes of the|vigilant|unsuspecting} {teachers|professors|instructors|faculty members}, a {roaring|booming|thriving|flourishing} trade in {talismans, amulets, and other protective devices|amulets, talismans, and various protective items|protective devices, talismans, and various amulets|magical protective items, talismans, and amulets} was {sweeping|spreading throughout|taking over|rapidly expanding across} the {entire|whole|} school.
{Meanwhile|In the meantime|At the same time|During this period}, {hidden {completely|entirely|} from the {watchful eyes of the|vigilant|unsuspecting} {teachers|professors|instructors|faculty members}|without the {teachers|professors|instructors|faculty members} {knowing|being aware|having any idea}}, {a {roaring|booming|thriving|flourishing} trade in {talismans, amulets, and other protective devices|amulets, talismans, and various protective items|protective devices, talismans, and various amulets|magical protective items, talismans, and amulets} was {sweeping|spreading throughout|taking over|rapidly expanding across}|{talismans, amulets, and other protective devices|amulets, talismans, and various protective items|protective devices, talismans, and various amulets|magical protective items, talismans, and amulets} were being {traded|exchanged|sold} at a {roaring|booming|thriving|flourishing} rate {throughout|across|all over}} the {entire|whole|} school.