After losing veteran Test prop James Slipper in the warm-up when his calf injury flared, the Brumbies' night went from bad to worse at Australian rugby's hoodoo ground Eden Park.
As well as Slipper's omission, the Canberra team were forced into another late change for the Friday night clash with flanker Tom Hooper ruled out through illness.Â
In the grand final, the Blues will take on the winner of the other semi-final, with the table-topping Hurricanes hosting the Chiefs on Saturday in Wellington.
The Brumbies, who have now failed to go beyond the final four for a third straight year, were targeting a fast start as they looked to become the first Australian team to win a play-off in New Zealand soil since the competition started in 1996.
But the Blues drew first blood with centre AJ Lam scoring in the second minute after they sent the ball wide to cross after a 14-phase build-up.
After a Brumbies penalty strike that lead was extended to 12-3 after eight minutes, with Blues hooker Ricky Riccitelli bagging a try off the back of a rolling maul.
Another Noah Lolesio penalty kept the Brumbies in the hunt but on the back of costly errors, the home side pushed the lead out to a commanding 24-6 after 20 minutes, with lock Sam Darry and winger Caleb Clarke crossing with ease.
To the Brumbies' credit they regrouped, and after winger Corey Toole came within centimetres of scoring, flanker Rob Valetini burrowed over with the teams going to halftime 27-13.
In greasy conditions the Brumbies continued to make uncharacteristic mistakes, with the Blues' stiff defence and dominant set piece keeping the pressure on.
Blues No.8 Hoskins Sotutu landed a hammer blow in the 59th minute, although flanker Luke Reimer replied to cut the margin to 14 points with 10 minutes to play.
But the final nail in the coffin came when the visitors lost lock Nick Frost to a yellow card for tackling a rival in the air, leaving the visitors to play out the match a man down.
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