Big things were expected of the 22-year-old when he burst onto the scene in 2010 and he appeared in Saints' back-to-back Grand Finals but he was forced to rebuild his career away from his home-town team after being shown the door last season.
He was snapped up by the Bulls in the close season and admits this weekend's fixture, brought forward from Sunday because of Bradford City's appearance at Wembley, is the one he has had his eyes on for some time. "My grandad rang me up when the fixtures came out and said 'you play them in round four'," Foster said.
"I feel I do have a point to prove, I'd be lying if I said anything else. When Mike Rush singled me out and dropped me out of the picture, it was tough to take at the time for myself and my family. I'll definitely be re-visiting some of those memories. It will get me fired up.
"It's not like revenge. It's professional sport and these things happen. But because of the way my time at St Helens kind of fizzled out, I'd like to remind them of some of the good things I did there and show them what they're missing because I've definitely come on as a player."
Jon Wilkin will captain Saints in the absence of Paul Wellens, who has a calf strain, and will be hoping to kick-start their season. They are currently outside the top eight after picking up just three points from the first three rounds but Foster expects them to be once more challenging for honours.
"I wouldn't be too worried if I was a St Helens fan," he added. "They're going to come good. I don't know if they're going to come good on Saturday but when it happens they're going to take some stopping. It wouldn't surprise me if St Helens went on to do 15 wins on the bounce, they're that good a team."
In Saturday's other game, Warrington will face a test of their strength in depth when they go to Hull without four of their most experienced players.
Tyrone McCarthy, James Laithwaite and Ben Currie have all been recalled from dual registration at Swinton to help plug the gaps in the pack caused by suspension to Ben Westwood and injuries to skipper Adrian Morley and Ben Harrison, while Stefan Ratchford continues at stand-off in the absence of Lee Briers.
The Wolves, one of only two unbeaten teams, have the chance to take over at the top of the table from Huddersfield, who are at Wakefield on Sunday.