Canterbury skipper Billy Harmon peeled off the back of a scrum to touch down for their opening try but Northland responded minutes later with some razzle dazzle rugby on the right wing.
A Pisi Leilua backhander found Macilai, who stepped infield and offloaded to Tua. Halfback Lisati Milo-Harris was the next receiver and he flicked the ball on to lock Allan Craig who ran a beautiful support line to score.
Northland's troubles began on the stroke of halftime when captain Matt Matich - playing his 50th game for the Taniwha - was sin-binned for a maul infringement that resulted in a penalty try to Canterbury.
With the Taniwha were a man down, Canterbury put the hammer down and hurt Northland in every facet of play.
Despite enjoying 67 per cent of territory at halftime, Northland were unable to sustain the pressure after the break - and everything that could possibly go wrong did go wrong.
With the last quarter remaining, Northland had conceded 11 penalties to Canterbury's two - rich fodder for the hosts to pile on more misery, bank maximum points and climb atop the points table.
Brodie McAlister and Ngantungane Punivai each scored a brace of tries to slam the door shut on Northland, who were missing key players Tom Robinson, Matt Moulds, Rene Ranger, Sam Caird and Josh Moorby.
Northland return home to host North Harbour in Whangārei next weekend.