It was a mistake by his opposite number, however, that gave Canterbury a stunning start, with Marty Banks misjudging his depth on a clearing kick. David McDuling charged down the punt, and won the race to the ball to open the scoring within 40 seconds.
While he had nothing to do with the opening try, Mo'unga played a large hand in the remainder of the clash, mixing aggressive running with silky stepping as he scored twice and set up two more.
His first involvement led to a try, making an initial break before re-appearing on the following phase to stab a kick through for Nathan Earle to win the race to the line and extend the hosts' advantage.
Despite dominating the contest, Canterbury found themselves in some strife when Earle was sent to the sinbin. 71% possession and three times as many running metres as their opponent soon seemed inconsequential as an opportunistic Tasman team snared a 13-12 lead.
However, for every Tasman burst, Canterbury found a response, with Mo'unga often at the heart of it. The Crusaders playmaker beat nine defenders in the first half alone, the majority in a stunning solo effort which regained the lead.
Tasman had a chance to make it a one-score game going into the half, but instead were penalised, with Alex Ainley being sent to the bin for a neck roll on the brink of halftime.
Such was the story of the night for Tasman, who fought to stay in the contest but could never close the gap. Tries to Rob Thompson and Mo'unga were matched by Billy Guyton and Jesse McDonald to give travelling fans a glimmer of hope, but once again, Mo'unga played match-winner by popping up a superb ball for Billy Harmon to crash over.
Tasman's will take plenty from a season which has cemented their remarkable rise. Now twice beaten Premiership finalists, the province has plenty of potential and will be favoured to remain as a contender in future.
However, the Canterbury crusade shows no signs of slowing down.
Canterbury 43 (R.Mo'unga 2, D.McDuling, N.Earle, R.Thompson, B.Harmon tries; J.Barrett 5 con, 1 pen)
Tasman 27 (S.Frizell, B.Guyton, J.McDonald tries; M.Banks 3 con, 2 pen)
HT: 22-13