Just eight days after losing 60-6 against Leeds Rhinos, and on the back of a three-game losing run, they vanquished much-fancied opponents to set up a Wembley date with St Helens on July 17.
Jordan Turner (3), Jesse Sene-Lefao, Paul McShane and Gareth O’Brien all scored tries as Castleford reached the final for the first time since 2014.
“There’s a big swing in games; we lost by 60 last week and they won by 60 (62-18 against Leigh) so you wouldn't have given us much chance,” said Powell, whose side led 19-0 at half-time.
“But I think that first half was near perfect.
“We got rattled a little bit by Warrington at the start of the second half but from one to 17 it was a courageous effort.
“And we showed what we’re about and we still care .
“I think there's been a few people doubting that and I'd like to say to every Castleford fan, I am concentrating on this job and all the players are."
Powell, of course, ends his near nine-year end reign at Castleford when he moves to Warrington at the end of the season.
Clearly, he has been upset by some of the criticism of him and his squad but they responded in perfect style.
“I wouldn’t doubt the commitment of anyone in our camp,” he said, Castleford showing that by scoring two tries in the second half when down to 12 men following Jacques O'Neill's sin-binning.
“It's ridiculous to do so and I’d say that to anyone.”
Eight players who didn’t feature against Leeds returned to action today with full-back Niall Evalds giving a “world-class” display in the eyes of Powell.
He added: “Quality players make a big difference.
“We’ve had boys working hard but when you have so many quality players missing that can happen.
“There’s been a lot of people jumping up and down which is crazy.
“I don’t understand that at all.
“But this is special and it was superb.”