BUFFALO — When Jessica Leclerc skated into the corner of the rink, she was already a blur. Up went an arm as she stopped, whistling a penalty. A decisive chop of hand on sleeve signaled a slash.

This is what hockey justice looks like — or would, if this were an actual game. It was just a drill. No actual hockey players had strayed or been punished, and Leclerc made for the blueline to do it all again.

Welcome to the National Hockey League’s officials combine, an annual late-summer festival of phantom calls and practice puck drops. Over four days in mid-August, 86 aspiring game officials from across North America convened at Harborcenter, the two-rink training facility next door to the Buffalo Sabres’ home arena.

Every spring, on the same ice, the N.H.L. puts the best draft-eligible players through their paces. This is a showcase like that one, but with fewer fans, not so much news media and many more striped sweaters. Instead of showing extravagant goals by, say, Sidney Crosby, televisions on the concourses ran highlight reels of mic’d-up referees.