By way of context, that equals Sir Richard Hadlee's best during an 86-test career. Wagner has achieved his mark from debut in 2012; Hadlee reached his between January 1974 (v Australia at Sydney) and March 1981 (v India at Auckland).
Wagner secured the last three dismissals. Until then the left-armer looked intense and/or disgruntled, as if he'd come back to his car and found a parking ticket on the windscreen. In the 79th over he rifled a delivery at Keshav Maharaj which climbed on him, rapt the gloves, and found its way to B-J Watling. His confidence soared.
South Africa went to lunch at 243 for seven and were 258 for eight when rain stopped play in the afternoon session.
De Kock was unfazed throughout, playing with freedom and a suppleness of wrist. His unorthodox on-drive of Wagner in the 61st over demonstrated his flair. He walked into the shot and clipped the ball past non-striker Faf du Plessis.
Such effortless stroke play included 11 fours and two sixes while he nursed the tail to 124 runs for the last four wickets.
Latham's fielding triumph came when left-arm spinner Mitchell Santner was introduced in the 62nd over. To his third ball, du Plessis tried to get cute as it pitched around off stump. He bent low and lapped it around the corner.
Under the lid, Latham moved to his right with the delivery and plucked a catch from nowhere out of sheer anticipation. It channelled the spirit of the world's premier short leg, and current match referee, David Boon. Du Plessis exited for a conscientious 53.
Latham soon pouched another, sprawling low to his right at second slip to remove Vernon Philander off Henry. He now gets a chance to rectify his lack of batting form after scoring 24 runs from three completed innings this series.
This is a test New Zealand must win to square the rubber 1-1 so they must chase the contest.
The weather forecast is grim, but the game is advanced.