Thompson was one of Auckland's outstanding players, locking the defence shut against a Northland side who struggled to get clear scoring opportunities, and also scoring the first goal with a rasping drive from a penalty corner.
''We just wanted to make sure we kept our basics up and linked up through all the layers. When we were all doing the little one percenters and everyone was doing their bit, it added up to a pretty good performance," Thompson said.
Auckland were 3-0 up by halftime, with further goals from striker Katie Glynn and midfielder Julia King, who celebrated her 100th match for Auckland along with team mate Danielle Jones.
Deanna Ritchie, Sam Harrison - another of Auckland's best players yesterday - and Monique Wilson scored in the second half.
It was a tough day for Northland, who were desperate for victory in front of their home crowd. However they were off the pace in the first half, didn't win a penalty corner until three minutes after halftime and were overrun by a clinical Auckland team.
Southern, like the Northland women, had been hoping for a maiden title but came unstuck in the shootout in driving rain. Neither side had been able to get an edge in the 60 minutes of a tight battle.
When Callum Bailey, then Kurt Shimmins had consecutive shootout attempts blocked by veteran Capital keeper Kyle Pontifex, Southern's fate was sealed.
Auckland finished third in the Challenge Cup, beating Midlands 3-2, the goals coming from Joe Crooks and a brace from national skipper Simon Child, the winner a classy reverse stick shot from a penalty corner. Nic Woods and Des Abbott scored for Midlands.
North Harbour finished fifth in the K Cup after a 5-0 win over Central, and sixth in the shield, after losing 3-2 to Canterbury.