The Ballydoyle handler has saddled five of the last 10 winners of the Listed contest and this year launches a three-pronged assault.
Ryan Moore has sided with Magic Wand, who is a half-sister to the 2013 Irish Oaks heroine Chicquita.
The three-year-old has not yet won after two attempts, but shaped with some promise when third on her seasonal debut at Leopardstown last month.
O’Brien said: “Magic Wand is a lovely filly and a sister to Chicquita.
“She’s had one run on bad ground this year and got a little bit tired.
Rather than go back for a maiden now, we’ll let them step into those races as if they won their maiden and they can go back for a maiden any time.
The Ballydoyle maestro’s son Donnacha O’Brien partners another maiden in Forever Together, while Seamie Heffernan takes the ride on Dramatically, who won at Naas last year and steps up in trip after finishing down the field in the Nell Gwyn at Newmarket last month.
“Forever Together hasn’t run this year and is still a maiden as well, but she’s ready to go. We were waiting on the ground and obviously you can’t wait too long,” the trainer said.
It will be a good experience for them and we’ll see how we go. We will all learn together.
There is a fourth Irish challenger in Gavin Cromwell’s Princess Yaiza, the mount of the track’s leading jockey Franny Norton.
The daughter of Casamento won twice on the all-weather at Dundalk during the winter and was last seen finishing third in the Listed Salsabil Stakes at Navan.
Cromwell said: “We’re very happy with her going there. Obviously we’re a bit disappointed with the draw (10 of 10), but if anyone can steer her round there, I think we’ve got the right man on board.
“I’ve never been to the races at Chester so I’m looking forward to it.”
John Gosden saddled the brilliant Enable to win this race 12 months ago and this year relies on the Coolmore-owned Award Winning, who won a minor event at Wetherby less than a fortnight ago.
Another leading contender for the home team is Nottingham maiden winner Kinaesthesia, trained by dual Epsom Oaks-winning handler Ralph Beckett, while Andrew Balding saddles the once raced Lingfield maiden winner Shailene.
Balding said: “She’s a filly we like a lot. We’re guessing a tiny bit.
“She goes very nicely at home. She lacks experience, but so do many of her competitors.
“We like her and she’ll come on.”