Trevor Cox scored once and set up three more for the Tigers, who scored six unanswered goals in the third period, and Curtis Valk had a goal and two assists. Miles Koules, Chad Butcher and Chad Labelle added a goal apiece to round out their club's offence.
Levi Cable and Landon Peel supplied the goals for the Ice, who lead the series 3-2.
Medicine Hat's Marek Langhamer made 23 saves for the win as Wyatt Hoflin stopped 44-of-53 shots for Kootenay.
The Tigers went 2 for 3 on the power play while the Ice failed to score on three chances with the man advantage.