The Dunedin team took any mathematics out of the equation with two wins against the West Auckland Admirals in Dunedin at the weekend, backing up a 16-1 thumping on Saturday with a 10-2 win yesterday.
The double victory means the Thunder has made the final for the first time, and will host the final.
The two wins took the Thunder to 32 points, equal with the Canterbury Red Devils, who beat the Southern Stampede 5-2 and 3-1 in Christchurch at the weekend, but the Thunder's superior head-to-head record over the Red Devils ensured the final will be in Dunedin on August 24.
The Thunder took control in the first period, picking up goals through captain Andre Robichaud and Luke Pickering to take a 2-0 lead into the changing rooms. A Shaun Harrison goal early in the second period had the Thunder sitting pretty with a three-goal lead.
However, the Admirals capitalised on some turnovers and scored firstly through forward Matt Fuscic before forward Frazer Ellis added another.
A goal later in the period to Thunder forward Benjamin Gavoille gave the Thunder some extra breathing room leading into the third period, and Robichaud said the lacklustre second period encouraged his side on to a strong final period.
''We had a bit of a talk about that in between periods,'' Robichaud said.
Whatever was said obviously worked, as the Thunder piled on six goals in the final period. Forward Paris Heyd (two goals), Gavoille, Martin Pokorny, Noah Leahy and Tristan Darling got in on the action to stretch the scoreline out to 10-2 by the time the final siren went.
''We came back strong in the third [period] and credit to the boys - they worked the whole game and it all pays off in the third period when guys are tired and you start to get more chances,'' Robichaud said.
''It's six months of work that comes down to the final, and to be able to host it is just awesome.''
Robichaud said the team would enjoy the fortnight off, as several players dealt with injuries.
''It's good for a couple of guys that have some niggles to work it out and see the physios.''
The Thunder had put itself into a strong position after the first game of the weekend on Saturday, celebrating Heyd's 100th game in the New Zealand league with a 16-1 thumping of the West Auckland Admirals.
Heyd scored three goals, while fellow forward Pokorny scored four of his own. Robichaud and Ben Roth scored two each, while Conor Harrison, Mitch Frear, Shaun Harrison, Mat Enright, Joe Orr and Remy Sandoy also got on the scoresheet.
The Southern Stampede finished in fourth place in the league on 23 points, seven points behind the Botany Swarm, which finished in third.
