The apartment house had a communal attic rarely visited by its tenants. The labeled boxes and cast-off furniture offered little intrigue, so few explored its depths. Then one rainy afternoon, I ventured there seeking solitude. Roaming beyond the beams of the lone ceiling bulb, I spied only cobwebs until I rounded the corner of a hulking armoire. Beyond this antique was unrelenting shadow, but I willed myself to advance. Then a grim bellow of thunder resounded, sending me to the floor. Prostrate on the splintered beams, my hands felt a shaft of cold steel and I could but imagine the evil article I’d encountered.What technique does the author use to build suspense in the excerpt?