"That's tremendous," Maryland's Brenda Frese said. "To be that focused in every game over three years is just tremendous."
Tillis' average had dipped from 18 points a game to 11.4, and she had averaged just 5.7 against six opponents before Thursday's win for the Blue Devils (15-1, 6-0).
"I was telling everyone, if there's anything else I can do, please tell me," Tillis said. "I was just praying as hard as I could to get out of it."
Alana Beard, leading the ACC in scoring with 19.7 points a game, had nine in just 21 minutes for Duke. She strained a groin muscle in practice Tuesday.
Monique Currie added 12 points and Lindsey Harding 10 for the Blue Devils.
Freshman Shay Doron scored 17 points to lead Maryland (12-6, 4-3).
Tillis' teammates supported her through what, for her, were the doldrums.
"I don't think we believe we can win a national championship without Iciss," Beard said.
And Tillis followed the advice of coach Gail Goestenkors to stop thinking so hard.
"Iciss did a really great job," Goestenkors said. "She let the game come to her."
Tillis scored 13 first-half points and Currie 10 as Duke took a 44-28 lead at the break.
Maryland made seven of its first 14 shots and led 19-18 after Aurelie Noirez hit a backdoor layup with 10:35 left in the first half. But the Terrapins missed their next five shots and nine of 10 as Duke reeled off an 11-3 run.
Duke scored the last nine points of the first half and the first seven of the second.
Doron had 14 points in the first half, but took just one shot after the break.
Tillis made five of her first eight shots and finished 7-for-12 from the field.
The Blue Devils made 31 of 67 shots (46.3 percent) and outrebounded Maryland 46-30. They held the Terps to 16-for-53 shooting (30.2 percent).