Iva-Keen had three hits and batted in seven runs to give Dodgers (9-5) some hope of hauling in runaway leaders Cardinals (13-1) when the competition resumes in late January.
The talented batter gave Dodgers a 3-0 lead in the first inning when his crisp double sent home all three men on bases.
He then returned in the fourth inning to belt a grand-slam (bases loaded) home run to complete the rout.
In between his hits, Dodgers were handed far too many runs from a Saints side that had to be bolstered by two Cardinals players for the game.
Wild pitches, defensive indifference and errors led to a flurry of runs for Dodgers and ruined the game as a contest.
In the feature game of the round, Cardinals emphasised their top-dog status with a tough 6-3 win over Dodgers.
It was scoreless through two innings as two lesser-heralded pitchers, Kruz Cleminson (Dodgers) and Mitchell Finnie (Cardinals), found their zones and got good infield support.
Finnie made the breakthrough when he stole second and then scored on a sacrifice fly, but Dodgers came back with two runs on an error.
The key inning was the fourth, and the big movers were Cardinals. A sacrifice fly, an error, a two-RBI Finnie single and an RBI Lyall Scott single made it 6-2 in the blink of an eye.
Dodgers could only crib back one run, and they may be wondering if that was their last chance to stop Cardinals charging to the title.
Cardinals took an early lead and cruised to a 7-2 win over Saints in the third game of the round.
Christian Amos ignited the game for Cardinals when he smacked a three-run homer in the first inning.
Saints fought back well through Michael O'Neill, who hit an RBI single in the first and scored on a wild pitch in the third, and the game was alive at 4-2 after four.
Cardinals put it to bed with four runs in the top of the fifth inning, the highlight of which was a two-RBI single to Ben Moodie.
Jacob Wedlock pitched well for Cardinals, giving up just three hits and striking out nine batters.
The Central Otago Panthers were unable to field a team for the final pre-Christmas round, but it is hoped they will be back on January 24 to continue the season.
