The Kiwis host Tonga on Sunday at Auckland's Eden Park, where a win or a loss by less than 17 points will secure a place in next week's Cup final in Sydney against Samoa.
Brown sat out last year's tournament due to a knee injury, with New Zealand missing out on the title decider after Isaiya Katoa sank a 75th-minute field goal to put Tonga up 25-24.
In his return this year, the Newcastle-bound No.6 proved the difference in the Kiwis' tournament-opening clash against Samoa.
He relished being "back in black", with 18 runs for 146 metres, two try assists and broke an 18-18 deadlock with a match-winning try in the 73rd minute.
Brown ran on to a Kieran Foran bomb and plunged over the line.
"Honestly, I don't usually go for those - it was a bit of a jump in hope and I came down with the ball," the 25-year-old said.
"It was a strange try, but I'll take four points when I can.
"I definitely missed it last year, just being in the camp, as we love coming in just for the vibes, and obviously it's an honour to wear the black jersey.
"Any opportunity I get, I'm putting my hand up straight away, so it's good to be back."
Brown felt his team finished their match strongly, but expected Tonga to be desperate to bounce back from their 34-6 loss to arch-rivals Samoa last round.
"Obviously, with one win, we've got a bit of momentum, but it's going to be another tough game this weekend," Brown said.
"Samoa played an unreal game - they were on the back fence and they needed to win a game to make the final and they've done a pretty good job.
"I feel like the result doesn't really represent what Tonga bring.
"They're going to be coming out firing and they're going to have a lot to play for too."
Powerhouse lock Jason Taumalolo missed the Samoa match with a knee injury, but will play his 50th Test for Tonga after defecting from the Kiwis in 2017.
It's a boost for coach Kristian Woolf's side, with Tonga losing prop Stefano Utoikamanu (concussion) and centre Rob Toia (foot).
The absence of Toia sees Panthers premiership star Paul Alamoti wearing the No.4 jersey.
Among the new faces in the New Zealand squad, utility Te Maire Martin returns via the bench for the first time since 2018, with Brown happy to see his "roomie" get a run.
"I'm rooming with Te Maire, so hopefully he brings the energy that he brings around camp into the game," Brown said.
"That is him, that's his role. Bringing energy is what we want from our 14.
"We want him coming on, running the ball and giving opportunities for the boys in the second half of the game when forwards start to get tired and we've just got to take the opportunities."
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