The Tactix had claimed just one win all season, but shone in their final game, earning 59 per cent possession and hoisting 21 more shots than the Mystics. It was a drastic turnaround after the two sides' earlier meetings, in which the Mystics claimed comfortable 12 and 24 goal victories.
"We've been hiding that all season, haven't we," joked Tactix goal attack Anna Thompson.
"We had nothing to lose and were much more consistent, I'm so proud of the girls."
The Mystics were without veteran defender Anna Harrison, but that didn't account for their sloppy display, with a slew of errors giving the Tactix deserved dominance.
"We didn't respond, it was incredibly painful to be watching," said Harrison, who will be a nervous observer on Wednesday night when the Magic take on the Stars.
"We can't be in a position where you're relying on other people, we needed to prove it and do it ourselves."
The Mystics only missed five shots, but their lack of ball retention saw them struggle to get the ball into the attacking third as they slumped to the stunning defeat.
The result means that the Central Pulse will host the preliminary final next Sunday. They can go into the playoffs on a high when they take on the 14-0 Southern Steel tomorrow night.