They recovered from 18-0 down to lead 24-18 but were level again at the break and all square at 30-30 until Danny Richardson’s 64th minute drop goal finally gave them the edge in a dramatic affair at Emerald Headingley.
It ended a three-match losing run for Castleford who had squandered big leads to lose against both Catalans Dragons and Wigan Warriors during that sequence since lockdown.
On the bizarre contest, Powell said: “It was just mad - the whole thing.
“We ended up 18-0 down and did some of the damage to ourselves but it was just incredible from there to fight back and win what was a tight, intense, end-to-end game.
“There’s lots to improve on but we needed to win so that was really important.
“We had some key players who really started to step up.
“Liam Watts was superb in the pack as was Paul McShane who was back to his best while Danny Richardson was outstanding.
“Then the second half was just a battle.”
It was a fifth win from 10 outings so far and Powell conceded the win - which saw tries from McShane (2), Michael Shenton, Richardson, Mike McMeeken and Grant Millington - was crucial in their hopes of making the top-four.
“It was really important,” he added.
“In the grand scheme of things we played Catalans, who are going really well, and St Helens and Wigan who have been, too, so it’s been a real tough reintroduction to the competition for us.
We’ve done some really good things but fallen off the horse a couple of times in games and then obviously that battle against St Helens is where we showed our toughness as a team.
"The big thing for me is just being more consistent as we do loads of good things and have lots of good players but they are just not consistent enough.
“We don’t concentrate well enough so I think there’s two things there we want to improve and we have spoken about that in the changing room.
“It was a huge, huge win for us. We had to win tonight. If we’d have lost you obviously always find a reframe on different situations but it would have been really difficult to start picking the pieces back up and finding your way into the top four.
“We couldn’t afford to lose any more ground.”
Meanwhile, Powell was delighted to see Junior Moors back in the side after a torrid run of injuries had seen him play just once in the last 15 months.
The veteran prop’s only previous match this term was against Wigan in February and the coach said: “It was good to get the big fella back out there.
“He’s been with us a while now and he’s an awesome player for us.
“The boys were made up to get him out there.
“He had a lot of defending to do and had not played for a fair while so he did tire but it was great to see him out there.”