In contrast to Taylor's aggression, McCullum was positively sedate opening the batting for the Volts. At one point, he had just 16 off 23, but that may have had something to do with New Zealand test hero Doug Bracewell bowling a four-over opening spell costing just 14 runs.
Once Bracewell bowled out, the regular McCullum returned as he reached 50 from 44 balls. Once McCullum was dismissed for 79 from 63 off the bowling of Jacob Oram, Otago were in the box seat and needed 10 runs in the final over.
It looked as though English allrounder Napier was to be the hero for the Stags, having held Otago to five runs from his first five balls, but de Boorder stole that accolade and, with it, the win.
There was also last-over drama in Rangiora as Canterbury threatened to chase down Northern Districts' 161-6 but, on this occasion, the bowling side emerged triumphant.
The visitors were sent in by Canterbury captain Peter Fulton and that looked a mistake as, after 13 overs, the Knights were 102-2 and well-placed to cash-in. But some tight death bowling from the home side, including a three-wicket final over by Australian-born quick Mitchell Claydon, restricted a Northern line-up boosted by the inclusion of four Black Caps.
A guiding knock of 75 off 69 from opener BJ Watling enabled the Knights to post a challenging score, while Claydon and former Pakistani international Yasir Arafat bowled eight economical overs between them to prevent that score from being insurmountable.
In reply, a 71-run fourth-wicket stand between Dean Brownlie and Shanan Stewart pushed Canterbury close, and some late big-hitting from Andy Ellis (42 off 24) left the Wizards needing 12 from the final over. But Tim Southee's clutch bowling proved the difference, as Canterbury came up five runs short.
At Colin Maiden Park, rain reduced the match between Auckland and Wellington to 12 overs a side, which was plenty of time for the defending champion Aces to take the honours.
Muttiah Muralitharan's return of 2-15 was not enough to prevent Auckland from posting a challenging 116-5 - a total Wellington never seriously threatened to reach. The Firebirds needed 20 from the final over with four wickets in hand, but Azhar Mahmood restricted them to nine to claim the win for Auckland.