Maguire, two frames down at the start of the match, reeled off five on the trot before a fightback from Trump.
After coming back to 5-4 the world number two made a half-century in frame 10 only for the Glaswegian to take advantage of a poor safety shot to seal his passage.
Trump made the best possible start to the match as he surged into a two-frame lead with scores of 67 and 74 to seize the initiative early on.
But the Bristolian could not sustain his clinical play as he twice faltered to allow Maguire to have the table in the third frame, and the Scot produced a break of 87 to reduce the deficit.
The world number six improved still further in the fourth frame with a score of 100, including a break of 59, to level up the match ahead of the interval as Trump saw his early lead eroded.
The 31-year-old made it three frames on the bounce as he cleaned up in ruthless fashion once more with a break of 66 to assume the lead for the first time in the match, and suddenly Trump was the man under pressure.
A fourth followed for Maguire, who was suddenly looking unstoppable, and a relentless break of 73 left Trump shaking his head in his chair, helpless to prevent himself from slipping two frames down.
Trump, by this point, was left looking utterly despondent sat in his chair as Maguire proceeded to end on a score of 95 in taking the seventh frame to further extend his lead and move to within a single frame of victory.
But the 23-year-old edged a scrappy eighth frame to reduce the arrears, capitalising on numerous mistakes from Maguire to close it out and make the Scot sweat.
He continued his momentum with an 86 in frame nine - which could easily have become a century - then made 50 dead in the following frame in seemingly no time at all.
However a misjudged decision to play a short snooker at the bottom of the table allowed Maguire to pot a long red, and he worked his way expertly around the table to take the lead in the frame.
Seemingly nerveless up to the brown, he cut an awkward blue to right middle after leaving himself short, which meant Trump needed two snookers.
He came close to finding one of them on two occasions before losing concentration and allowing Maguire to pot a short pink and give himself a chance of claiming a fifth ranking title on Sunday.