Fraser snapped a shot through the legs of Mathieu Corbeil-Theriault for his second goal of the game. Drew Czerwonka, Kevin King and Jesse Ismond had the other goals for WHL champion Kootenay. Nathan Lieuwen made 19 saves in goal for the win in front of a packed house at the Hershey Centre in Mississauga.
Tomas Jurco had a pair of goals for the QMJHL champion Sea Dogs, including the game-tying goal that bounced off his head and in behind Lieuwen with just 15 seconds left in regulation.
Ryan Tesink and Kevin Gagne scored the others for the Sea Dogs. Corbeil-Theriault stopped 40 shots in defeat.
The Owen Sound Attack and the Mississauga St. Michael's Majors wrap up round-robin play Wednesday. The winner of the matchup of OHL rivals will clinch a spot in Friday's semifinal, while loser will face the Ice in a third-place tiebreaker Thursday.
Saint John already clinched its berth in the final with a thrilling come-from-behind overtime victory over the Attack on Monday. The Sea Dogs now have four days off before the championship game on Sunday.
The game started slow, with no scoring and few quality scoring chances in the first period.
The pace picked up in the second with the teams trading a pair of goals each. Saint John opened the scoring at 1:26. Zack Phillips fed Tesink, who ripped a wrist shot top corner past the six-foot-five Lieuwen from the high slot.
The Sea Dogs made it 2-0 at 5:33. Stanislav Galiev dished to Jurco, who deked Lieuwen to his glove side and lifted a backhand that bounced off the goaltender and the crossbar before trickling over the goal line.
Kootenay finally got on the board with a power-play goal at 13:17. Czerwonka picked up a James Martin dump-in behind the Sea Dogs' goal and scored on a wraparound.
The Ice then tied the game less than two minutes on a 5-on-3 power play. Reinhart made a soft pass to McNabb who blasted a one-timer that King tipped past the six-foot-six Corbeil-Theriault.
Kootenay took its first lead of the game just 23 seconds into the third period when Ismond, left alone in front, slapped a rebound into the open net. But the lead lasted less than two minutes when Gagne snapped a shot between Lieuwen's legs at 2:10 to tie the game at 3-3.
The Ice retook the lead at 7:19 with another power-play goal. Reinhart took a pass from McNabb and made a cross-ice feed to Fraser, who fired it past a diving Corbeil-Theriault. The lead held until Jurco took a Phillips shot off his head to tie the game at 19:45 of regulation to set up overtime.
The Ice faced a depleted Sea Dogs' lineup. With its spot in the final guaranteed, Saint John rested regulars Michael Kirkpatrick, Simon Depres, Steve Anthony and Danick Gauthier. Monday's overtime hero, Jonathan Huberdeau, dressed but saw limited ice time.