Dickson finished the game with four goals and an assist to lead the Roughnecks (5-10). Shawn Evans scored a hat trick while Geoff Snider and Jeff Shattler rounded out the attack.
Ben McIntosh chipped in with three goals for Edmonton (9-5) while Mark Matthews struck twice. Robert Church, Adrian Sorichetti and Zack Greer added the others.
Frankie Scigliano made 41 saves for the win in goal. Aaron Bold turning away 33 shots in defeat.
Calgary went 0 for 1 with the man advantage with the Rush converting twice on seven opportunities.