Clive Griffiths is now only a handful of players short of completing his Knights squad after snapping up Nottingham flanker Phill Eggleshaw.
The 24-year-old has played his entire professional career with Nottingham but saw his last campaign blighted with a cartilage injury to his shoulder.
The 6ft5 back-rower possesses plenty of pace and is strong in defence.
Eggleshaw’s arrival boosts the Knights’ squad up to 24.
Griffiths has targeted a squad of 28 to tackle National One next season.
Hooker Ben Hunter moved to Castle Park earlier this week.
The 25-year-old is the third Hooker to join after Roberto Santamaria signed and Jack Bergmanus extended his stay.
Hunter came through the ranks of Hartpury College before playing in National One with Cambridge and Ealing.
Former centre favourite Bevon Armitage made his return to Castle Park from Plymouth last week while winger Tyson Lewis extended his Knights stay.
The Knights’ friendly with Rotherham Titans, due for August 24, has been cancelled.
Instead, Leeds Carnegie will visit Castle Park for a warm-up game.
Castle Park has been chosen as one of the venues for a special double-header round of fixtures which will open the new Championship season.
Each side in the division will play an additional game next season with neutral venues chosen to host two fixtures on the same day.
Castle Park will host Rotherham Titans v Moseley and Leeds Carnegie v Nottingham on September 14.