The 31-year-old has endured a difficult campaign with his case for wrongful dismissal against former club Huddersfield Giants long looming over him.
However, he successfully won the case last month and received around £167,000 in damages.
Mason, who joined Castleford on a 12-month deal after their West Yorkshire rivals axed him over an inappropriate picture on his Twitter account last October, returns to the side for the first time since tomorrow.
“He’s had a fair period of frustration with the court case,” admitted Powell, ahead of Warrington Wolves’ visit.
“He’s obviously happy to get a fair chunk of money and to be seen to be right in the whole affair.
“It’s a fair weight off his mind now and hopefully he can focus on his rugby and finish the season really strongly. He’s been around the game a long while, is a big, physical player and he’s looking forward to finishing off on a high.
“With those frustrations behind him that should happen.”
Mason’s availability is welcome news given Powell is without two other props from the side that lost at Huddersfield a fortnight ago.
Jonathan Walker injured his knee, Ben Davies has since left the club and joined Halifax while back-row Oliver Holmes (ankle) is another casualty.
However, as well as Mason, forwards Ryan Boyle and Charlie Martin return from suspension and a loan spell with Featherstone Rovers respectively to aid Castleford’s cause.
Twelfth-placed Tigers were six points adrift of Hull FC in eighth ahead of this round, with just five games to go, but Powell has not written off their play-off chances.
“It’s a tough one,” he said. “Hull are in the box seat but they’ve obviously got the Challenge Cup final so you don’t know how that’s going to impact on them.
“While ever it’s mathematically possible you’re fighting for it.”
Powell is just keen to see some regular form from his frustratingly inconsistent side.
They have shown flashes of brilliance but either start or finish badly, something they can ill-afford to do against a Warrington side who were denied a Wembley place by Hull on Sunday.
“They’ll be fired up and we know they’re strong across all areas, so we have to be right on top of our game” he added.
Warrington are without a couple of notable performers in veteran Australian full-back Brett Hodgson and compatriot Michael Monaghan plus Mike Cooper.
However, England scrum-half Richie Myler is expected to return.