{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.
{Meanwhile|In the meantime|At the same time|During this period|Simultaneously}, {hidden {completely|entirely|cleverly|} from the {watchful eyes of the|vigilant|unsuspecting|oblivious} {teachers|professors|instructors|faculty members|staff}|without the {teachers|professors|instructors|faculty members|staff} {knowing|being aware|having any idea|suspecting anything}}, {a {roaring|booming|thriving|flourishing|bustling|lucrative} 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|charms, talismans, and magical protective objects} was {sweeping|spreading throughout|taking over|rapidly expanding across|gaining popularity 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|charms, talismans, and magical protective objects} were being {traded|exchanged|sold|bartered|passed around} at a {roaring|booming|thriving|flourishing|frantic|astonishing} rate {throughout|across|all over|in every corner of}} the {entire|whole|expansive|sprawling|} school{| grounds| campus}.