Exeter reached a fourth successive Premiership final after beating play-off rivals Northampton 42-12 at Sandy Park.
The Chiefs will face title holders Saracens at Twickenham next Saturday – the third time in four years for those clubs to contest English rugby's biggest domestic prize, and a repeat of last season's final.
A week after defeating Saints 40-21 on the final day of regular season action, Exeter again powered to victory following a tight opening 40 minutes.
Exeter, though, pulled away during the third quarter as lock Dave Dennis and wing Tom O'Flaherty added further scores.
Substitute Sam Simmonds then claimed a late score, as did centre Sam Hill, with Simmonds' brother Joe converting all six tries for a 17-point haul.
The Chiefs were champions in 2017, beating Wasps after extra-time, but their two previous showdowns with Saracens ended in defeat.
Exeter made one change to their starting line-up, with O'Flaherty replacing Olly Woodburn, while Northampton handed Fish a start instead of the injured Reece Marshall.
Props Francois Van Wyk and Ehren Painter were also called up, but there was no role for Dylan Hartley, who is back in training but has not played since December due to knee trouble.
The Chiefs sacrificed an early kickable penalty and saw flanker Dave Ewers held up over the line by Saints scrum-half Cobus Reinach's tackle, and it remained scoreless after 15 minutes.
Northampton, though, could not hold out for much longer and Exeter went ahead when Williams powered over from close range for a try that Simmonds converted to confirm Chiefs' dominance.
Saints could not make an impression on the game, and with Exeter continuing to opt for touch rather than kick for goal, that approach was rewarded after 22 minutes with a second try.
Centre Ollie Devoto proved an impressive creative force in midfield, but Simmonds still had plenty to do, yet he beat two defenders comfortably and touched down for a score that he also converted.
But the game took an unexpected turn as Saints scored 12 points in two minutes, responding to a sizeable deficit in sparkling fashion.
They opened their account through a penalty try awarded against O'Flaherty – he was yellow-carded by referee Matt Carley for an illegal challenge that prevented Fish from grounding the ball – then conjured a wonder-try.
Scintillating off-loading sparked by wing Tom Collins' brilliant catch and sprint involved Tuala and centre Rory Hutchinson before Tuala crossed.
Biggar could not convert, but Northampton were well and truly back in the contest, trailing by just two points approaching half-time.
Just as quickly as Northampton fought back, though, so Exeter pulled away again, scoring two tries in three minutes shortly after the break.
Dennis crossed following relentless forward pressure for Chiefs' third try, then O'Flaherty produced a 50-metre solo spectacular, breaking clear before leaving Biggar rooted to the spot as he scorched outside him and finished majestically.
Simmonds kicked both conversions, and Exeter led 28-12 with more than 30 minutes of the contest remaining.
Northampton, this time, had too much of a mountain to climb as the Chiefs booked another appointment with Saracens at English rugby headquarters, scoring 28 unanswered second-half points.