Having momentum on their side as they headed into the final turn with their noses in front for the first time, it was thought the more experienced Mystics would seize control in the fourth period. But they could never shake free of the determined Tactix, and when Jade Clarke picked up an errant pass from the Mystics with less than a minute to go, the home side were able to draw level.
English import Jo Harten, who had been impressive in-goal for the Tactix all night, had the opportunity to win the game with a penalty shot at the end of regulation time, but her shot cruelly bounced out of the goal to force the game into extra time.
The Mystics again looked like they were close to sealing the game, leading with less than a minute to go, but a poor feed from rookie midcourter Elisapeta Toeava gave the Tactix a chance to level the score again at the end of the two seven-minute periods. At that point, the game was there for the taking for the first team to lead by two goals.
The tired and frustrated Mystics side were the first to blink, and Harten made no mistake with her second opportunity to close out the match.
Leaking on average 71 goals a game over the first three rounds, the Mystics went into the match as the worst performing defensive team in the league.
It was thought against the Tactix - a side that committed 37 turnovers against the Vixens last week - the Auckland side would be able to generate more defensive stops.
But the Mystics looked just as slow against the inexperienced Tactix line-up, struggling to disrupt their flow early on as the home side raced out to a big lead.
The loss of young shooter Sophia Fenwick mid-way through the second spell slowed the Tactix momentum, with the home side forced to introduce Julianna Naoupu, who is still making her way back from knee surgery in the off-season, earlier than they had hoped.
Tactix 80
Mystics 78