Victoria now has a 2-1 lead in the best-of-seven series for Canada's senior indoor lacrosse championship.
Jeff Shattler had a pair of goals and four assists for the Shamrocks, while Scott Ranger, Karsen Leung and Mitch Jones chipped in as well. Goaltender Matt Vinc made 37 saves for the win.
Steven Keogh and Kasey Beirnes scored two goals each for Six Nations, while Roger Vyse and Cody Jamieson had goals too.
Brandon Miller and Evan Kirk split time in the Chiefs' net. Miller stopped 28-of-31 shots in 42:18 of work, while Kirk turned aside 10 of 15 in 17:42.
Six Nations squandered a 6-4 lead after two periods, letting Victoria outscore the Chiefs 5-2 in the final 20 minutes of play.