The 21-year-old center registered a hat trick and collected two assists in the Armada's 6-1 victory over the Charlottetown Islanders in Game 7 of their semi-final series.
Alain's five points set a new franchise mark for the most points registered by an Armada player in a single playoff game.
Head coach Joel Bouchard's contingent will now square off against the Acadie-Bathurst Titan for the right to earn a spot in the Memorial Cup, which gets underway later on this month.
For his part, Alain leads the QMJHL in playoff scoring with 16 goals and 28 points in 16 games. Thirteen of those points (7g, 6a) have come on the power play, and three (1g, 2a) were registered while the Armada were short-handed. He also ranks second with a plus-18 differential during the postseason.
The Canadiens signed Alain to a three-year entry-level contract on April 24.
The Quebec City native was the QMJHL's third-leading scorer during the regular season with 87 points (44g, 43a) in 65 games, including a league-leading 21 markers with the man advantage.
