Wray buried Brannon's centering feed to open the scoring with first of five straight Rapid City goals at 5:02 of the first period.
Jesse Schultz doubled the Rapid City lead by scoring from the doorstep just one minute and 19 seconds into the second period. The gap stretched to 3-0 when Brannon fired the puck home from the high slot at 8:48 of the second.
The Rush pulled away by scoring two more goals in the third period. Stroh pounced on a rebound just 31 seconds into the third and Wray jammed in Brannon's centering pass at 10:56.
The Mallards' Jeff Lee crashed the net to spoil Boron's shutout bid with just a minute and 19 seconds remaining in the contest, but by then the issue was no longer in doubt.