After dominating both splits of the competition last year, Mt Roskill Grammar School were sensationally upset 2-0 in the semifinals by Rangitoto College last week.
Rangitoto haven't dropped a game during the playoffs and will meet Mt Albert Grammar School in the decider after the Aucklanders beat Tawa College 2-0 in their final-four clash.
Many were tipping Mt Roskill to continue their dominance in this split but Rangitoto made the most of their opportunity.
They haven't always had their fair share of TV exposure this year but all eyes will be on them during today's grand final that gets underway at 5pm. It will be broadcast live on Sky at 5pm and streamed online on Twitch.
"Rangitoto felt upset that they weren't given the respect they deserved," HSL tournament director Matt Ross said.
"Now they've earned that respect and I imagine they'll want to show the entire country how good they are in the grand final of the HSL's Premier Division."
The final will be played across a best-of-three format as New Zealand's top League of Legends school will emerge.
Rangitoto's semifinal victory over Mt Roskill ranks as the biggest upset in the short history of the HSL and has increased the interest in today's grand final.
"I went to check on the MAGS boys after they won their semifinal and they seemed excited about the prospect of winning the whole thing," Ross said.
"They didn't expect to play Rangitoto and the first thing I heard them say was: 'We can win this'.
"Mt Albert seem confident now they're playing Rangitoto instead of Mt Roskill but I think they should be worried. It's no fluke to take down the returning champions 2-0 in a best-of-three competition."
As the split draws to a close, Ross said it had been another strong instalment of the competition as the popularity of esports continued to grow in New Zealand.
"HSL has been a fantastic success so far this year. More and more schools are signing up to be part of the second split.
"I've had so many students send their thanks to HSL for giving them the opportunity to take part in the competition."
In the Challenger Division grand final, ACG Senior College will meet Whangaparaoa College.
ACG beat Manurewa High School 2-0 to advance to the final, while Whangaparaoa eased past the Mt Roskill Challenger side by the same margin.
