Maddinson got out of the blocks quickly, kept his cool when four wickets fell in a clump, and put his foot down again late to lift the Renegades to 7-166 batting first in Cairns after the Heat sent them in.
The 30-year-old took 20 off Xavier Bartlett's second over and a further 22 off his third in a 49-ball innings, including 10 fours and three sixes, that produced his highest score in T20 cricket.
West Indies international Andre Russell (35 off 28 balls) celebrated his return to the Renegades with a powerhouse innings including three sixes.
The visitors rocketed to 0-65 off six overs before Sam Harper (21) was well caught at fine leg by Josh Brown off the first delivery bowled by the impressive James Bazley (2-19 off four).
The Renegades lost 4-22 in six overs due to some shrewd captaincy by Heat skipper Jimmy Peirson and smart bowling by spinners Mitch Swepson (1-30) and Matt Kuhnemann (3-32).
Swepson knocked over Jake Fraser-McGurk (three) with a classic googly. Then Kuhnemann took two wickets in one over by slowing down his pace and bamboozling Aaron Finch (four) and off-season recruit Jono Wells (one).
That was when Maddinson and Russell took control in a 78-run stand off 46 deliveries.
Maddinson, when on 42, was involved in a bizarre incident when he played a pull-shot off Mark Steketee.
The ball lobbed over the stumps but one bail came off.
On review it was clear that the dislodged bail was an unexplainable mystery but no fault of the batter.
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