In the semifinals, Marton were able to avenge their eight wicket loss to Renegades seven days before on March 9, by upsetting them by three wickets.
Marton bowled the favourites out for 116 in the 30th over, then a lower order fightback saw them sneak home with 118-7 in 36 overs.
Aaron Smith was the matchwinner, taking 6-30 with the ball, before scoring 20 not out in 10 balls coming in at No 9 to get his side home.
United got payback on the Wicket Warriors with a comfortable eight wicket win in the other semifinal.
They bowled the all-Indian club out for 121 by the 33rd over, with Steve Meredith, Sam Roebuck and Lovedeep Singh taking three wickets each.
United took their time, but reached 122-2 by the 35th over, with Alan Kenny unbeaten on 41 after joining opener Karl Bremer (25no), who anchored the chase.
In the season statistics, Marton's veteran batsman Andrew Spence is the leading P2 scorer, having made 311 runs from his nine innings at an average of 38.88, including 104 not out in the four wicket loss to Whanganui Collegiate 2nd XI on November 24.
United's Meredith is the season's best wicket taker, with 16 scalps from eight games and an economy rate of 2.78 runs per over, with his best figures being 4-22 in the three wicket win over the Warriors on the same day in November.
The final will start at 12.30pm.