The classy league leaders were immense yet again on Saturday as, not for the first time this season, they vanquished high-class opponents with alarming ease.
Eden took his tally for the season to 18 with his treble coming inside 19 second-half minutes while fellow wideman Greg Minikin also grabbed a brace as did Jake Webster, the veteran centre celebrating signing a new one-year deal at Wheldon Road.
Furthermore, Castleford completed this 10-try masterclass without Rangi Chase, the maverick former England stand-off not in their line-up with the club investigating an alleged incident involving him at Featherstone Rovers’ Challenge Cup win over Halifax on Thursday night.
Young half-back Tom Holmes, who had only previously started four games for his hometown club and hails from nearby Lock Lane, came in alongside man-of-the-match Luke Gale but certainly did not look out of place as the hosts destroyed woeful Saints and claimed their place in Sunday’s quarter-final draw.
The only downside was the sight of Zak Hardaker, their England full-back who has thrived on a season-long loan from Leeds Rhinos, being helped off with an ankle injury in the 77th minute as Tigers won for the first time in six meetings with these opponents.
Daryl Powell’s side - whose one of only three defeats this year was a 26-22 loss at Saints on Easter Monday - took control of the game with a brilliant purple patch of 21 points in just eight remarkable minutes before the break.
The genesis for all that though, when the West Yorkshire club demonstrated once more their ruthless cutting edge, was a crucial defensive show just beforehand.
After Ryan Morgan leapt in front of Greg Eden to claim Matty Smith’s crossfield kick and nudge back to 10-4 in the 17th minute, St Helens actually threatened to make this a proper Cup tie.
They pressed hard for the next 15 minutes or so, encouraged as Castleford made a series of uncharacteristic errors, squandering possession in their own half and conceding soft penalties.
However, Powell’s side are made of stern stuff nowadays; each time they erred, they defended their line fiercely, dismissing anything and everything that Saints threw at them.
Zeb Taia was inches short, Michael Shenton shot out to shut down Theo Fages, Junior Moors halted another Saints player storming towards the post and, finally, Eden safely claimed Matty Smith’s latest kick before also being tackled in the air by Adam Swift.
Within seconds, after clearing their lines with the resulting penalty, Castleford crucially scored at the other end.
Webster sneaked into snatch Benny Roberts’ lofted chip in front of the rooted Regan Grace to scored his second try of the afternoon and so began that ruthless spell.
Gale converted for 16-4 and, when Eden brilliantly collected the England scrum-half’s low pass from almost off the ground, the winger sped clear on a dazzling run.
James Roby finally brought him down but Saints were all at sea and, two tackles later, Paul McShane spun out of some attempted challenges to cross again.
They added a third back-to-back when Roberts sprinted clear from deep and then showed great poise to dab a grubber forward that bounced up perfectly for Minkin.
They could not make it four tries in as many sets but Gale did, at least, claim a drop goal to heap the misery on further.
And the lack of a try was only a minor blip, too, quickly atoned for in the following set as Tigers marched downfield once more for Nathan Massey to plunder over.
Gale had missed three of his five conversion attempts, too, but his third success put the hosts in 31-4 ahead at the break. Game over.
Some fine offloading in the 44th minute saw Eden scurry over in the corner for his first and - after Swift denied Holmes with a quality cover tackle - he added his second soon after when advancing onto Gale’s long looping pass.
The former Brisbane Broncos winger claimed his third after the hour mark, benefitting from more clinical handling from his centre Shenton, the captain who had opened the scoring with a third minute try.
Minikin added a superb 60m solo try and all Saints could muster was Luke Douglas’ 74th minute effort, by which time they had been completely embarrassed by another outstanding Castleford display.
Castleford Tigers: Hardaker; Minikin, Webster, Shenton, Eden; Holmes, Gale; Lynch, McShane, Millington, Sene-Lefao, Milner. Substitutes: Massey, Roberts, Moors, Cook.
St Helens: Makinson; Swift, Percival, Morgan, Grace; Fages, Smith; Walmsley, Roby, Douglas, Taia, Knowles, Thompson. Substitutes: Amor, Wilkin, McCarthy-Scarsbrook, Richards.
Referee: Phil Bentham (Warrington)