Louisiana State scored 32 points in the second quarter of the N.C.A.A. women’s championship game, setting a tournament record for most points in a quarter. At the end of the half, the Tigers had 59 points, setting another record, for most points in a half. They set one more at the buzzer, with the most points scored in a tournament game, as they defeated Iowa, 102-85.

L.S.U. can thank Jasmine Carson for that.

Carson, a 5-foot-10 guard from Memphis who is in her final year of eligibility with the Tigers, led L.S.U. in the championship game on Sunday with 22 points, almost all of which came in the first half with a 3-point barrage after she entered the game as a reserve when the team’s leader, Angel Reese, got into foul trouble.

She made all five of her 3-point shot in the half, including a bank shot at the halftime buzzer that sent the gold-and-purple-clad fans in the American Airlines Center to their feet.

It was a turn of events worthy only of the N.C.A.A. tournament. Iowa and Caitlin Clark, the best 3-point shooter in the country, lost to L.S.U. and its flurry of perimeter shots from a breakout athlete few may have heard of before Sunday afternoon. In her perfect first half, Carson had one more 3-pointer than Clark in five fewer attempts, and hit all seven of her shots and both of her free throws.

Carson said that when she woke up Sunday, she had winning on her mind and was ready to “do anything” that her team needed. She delivered, and then some.

“This is the game of my life,” Carson said. “I won a national championship on the biggest stage possible.”

L.S.U. Coach Kim Mulkey has consistently referred to her team as a big puzzle, with nine transfer players. Carson, one of those transfers, had started 30 games this season before being relegated to bench minutes during the tournament. But she has been the 3-point leader of that puzzle this season.

“She can just light it up,” Mulkey said.

Carson came to L.S.U. this season after two years at West Virginia, where she shot 45.3 percent last season. She also spent two years at Georgia Tech.

But she wanted to finish out her college career under Mulkey.

“I’ve been working hard my whole life, and I came to L.S.U. just to contribute and win a national title,” Carson said. “I wanted to play for the Hall of Fame coach and play with great players.”

“I couldn’t have wanted a better ending than for it to end like this,” she added.

Mulkey said the Tigers won the game in the second quarter with leadership from Carson, Last-Tear Poa and Sa’Myah Smith, when the three of them “got in there and they extended the lead and scored with Iowa,” as the Tigers grew their lead to 17 at the half. “I thought, this is going to be a fun night. They didn’t just keep it close, they went in and they attacked.”

Carson’s attack in the first half surprisingly gave way to a much more quiet second, in which she played only 10 minutes and missed her only field-goal attempt. She hit one of two free throws to increase her team-leading scoring total by a single point, as Mulkey turned mainly back to Reese and the rest of the starters to close out the win.

Reese, who was named the most outstanding player of the Final Four, said the win was “bigger than her,” and she attributed the team’s success to the “supporting cast,” including Carson, adding, “everybody has played a role this weekend.” Carson was also named to the all-tournament team.

Alexis Morris, a fifth-year point guard, said she gave Carson clear instructions after she nailed her first few shots on Sunday.

“Stay right there, stay locked in, whatever head space you’re in right now, do not check out, just stay ready,” Morris said after the game. “She gave us a huge spark off the bench today. She was the game-changer tonight.”

Carson heard Morris loud and clear.

“I was just living in the moment. Usually I don’t even celebrate after I make a shot, but tonight I just let it all out,” she said. “I just had to let it out, you know. I didn’t have nothing to lose.”