The Rockets (23-7), move to Friday night's title game versus host MTCS (14-14), who beat second-seeded Community 58-49 in the second semifinal Tuesday night.
The two teams have split a pair of games this year with Forrest winning 63-61 in Murfreesboro on Jan. 24 and the Rockets' only league loss this season was a 68-66 Cougar victory in Chapel Hill on Dec. 12.
Forrest and MTCS will host first round Region 5-A Tournament games on Feb. 25, while Cascade and Community will have to travel to take on their District 10-A opponents.
"No matter what happens now, we will host a first round region game," said FHS head coach Wes Hobbs. "But, before that we get a chance to come back here Friday and play for the championship and we will be ready, this time hopefully from the beginning."
The Rockets led 8-7 after a Colby Anglin three-pointer midway through the first period before the Champions went on an 11-3 run to end the quarter with an 18-11 lead.
Will Holt and Bryce Clinton both hit three-pointers during the run for Cascade, who kept the pressure on the Rockets to begin quarter number two as they scored the first six points of the period to take their biggest lead of the game at 24-11.
A Zach Horvath trey with 3:40 remaining in the first half stopped the bleeding, but the Rockets still trailed 26-15, entering the third period.
Mark Pope stole the rock from Cascade and scored to begin the second half, but Blake Floyd came right back with a bucket for the Champions.
Several possessions later, Pope scored again, and after a Cascade miscue, Marshall Hunter drilled a long bomb to make it 28-22.
The two squads traded buckets, and with just over two minutes to play in the period, Tyler "Juice" Rumley put the squeeze on the Champions with a three-pointer to cut the Cascade lead to 30-27.
The Champions coughed up the rock moments later and Rumley went downtown again to tie the contest at 30 with 1:13 left.
"We needed that third quarter big time," said Hobbs. "What I liked was the guys came into the locker room after the worst first half we had all year and they didn't seem down. They were talking each other up, they were saying, we could do this, we could do this."
Cascade dug in and came back, taking their last lead at 36-35 on a Jesse Barnes basket, but the Rockets would go take a 39-37 lead with 3:37 remaining in the ballgame on a beautiful back-door drive by Anglin.
Clinton re-knotted the contest with two free throws, and after Floyd's third blocked shot of the game at the other end, Cascade had the ball, but could not score.
Forrest set up another play, and this time it was for Pope, who hit nothing but the bottom of the net on a deep corner three-bomb to give Forrest a 42-39 lead with 1:33 remaining in the game.
Cascade missed again and now they were in trouble because the Rockets had only one team foul in the half, so the Champions fouled the Rockets five consecutive times to put Forrest at the line in a one and one situation with 19.2 seconds left.
The Rockets missed the front end, but the Champions could not score on two attempts at the other end and after another missed foul shot by the Rockets, the time ticked away as Cascade heaved up a wayward desperation shot as the buzzer sounded, ending the game.
Rumley and Pope led Forrest with 11 points apiece, Hunter scored nine (3 treys), Anglin ended up with seven, Horvath had three points, and Zach Ray had one point.
Barnes scored 10 for Cascade, Pimental and Floyd scored nine apiece, Holt netted six, Clinton three, and Anthony Marable rounded out the scoring on the night with two points.