Rhys Duch and Jesse King each had a pair of goals and two assists to pace the Shamrocks, who improve to 10-4, four points behind the league-leading New Westminster Salmonbellies, who are 11-3-2 and on a five-game win streak.
Corey Small, Doug Langlois, Myles Kenny, Paul Brebber, Chris Wardle, Ian McShane and Ethan Garland also scored for the Shamrocks, who let a 7-3 lead get away from them just over halfway through the second period.
They trailed 8-7 6:49 into the third before rattling off four straight goals.
鈥淚t wasn鈥檛 our best performance, by any stretch. Our first period was sluggish. The second period we played well for the first 14 minutes then lost a little mental focus in terms of defensive breakdowns,鈥 said Shamrocks head coach Bob Heyes.
鈥淲e worked hard, but we didn鈥檛 work smart at times and that鈥檚 a little frustrating. It got us in the playoffs, though. That was our first goal and the next step is still building our game and getting to that next level.鈥
James Rahe, with a hat trick, Jordan Dance, Jakob Doucet, Mitch McMichael, Brandon Bull and Bryce Brochu replied for the basement-dwelling Thunder, which falls to 3-13.
Cody Hagedorn made 35 stops in goal for the Shamrocks, while Brodie MacDonald stopped 37 for Langley.
Victoria, which has two games in hand on New West, has tonight off before returning to action on Friday at The Q Centre with the 9-6-1 Burnaby Lakers paying Colwood a visit. The Shamrocks then head to Coquitlam on Saturday night to face the Adanacs, who were eliminated from playoff contention with Victoria鈥檚 victory on Wednesday.