Champion trainer Jason Thompson expects the topically named Immunity will prove “very hard to beat” in the heats of the Trio’s Winter Cup (520m) at her home track of Cranbourne on Saturday night.

Immunity, a half-sister to Thompson’s former star Black Opium and littermate to Equalizer, runner-up in the Group 3 Bill Collins Speed Star at Sandown on Wednesday, returned to the track last month after a seasonal spell and has taken up where she left off.

She’s won at Warragul (25.51sec) and Sandown (29.32sec) in fast time and finished third to eventual winner Qwara Bale in a heat of the G1Sapphire Crown.

“She’s had three runs back after nearly five months off and had two wins and an unlucky third, so she’s come back as good as ever,” Thompson said.

“She’s very good and very honest. Her record tells you that – she’s won 13 from 18 with three placings, so she’s only been out of the money twice.”

Immunity is ideally drawn in box eight, from where she’s won all three career starts, for what will be her Cranbourne debut in the fourth and final heat of the Winter Cup, which is Race 8 at 7.10pm.

“She’s beautifully boxed; she’s never been beaten from out there,” Thompson said.

“Even though she does like the inside, she really knows how to use box eight.

“She’s never been around Cranbourne but that doesn’t worry me at all. She’s going well and she’s pretty adaptable. It will more come down to how she begins and she’s pretty reliable out of the boxes.

“I think she’ll be very hard to beat. Her record tells you that, her consistency tells you that and she’s won three out of three from box eight.”

WATCH: Immunity (8) displays ‘resilience’ with a smart last-start 29.32sec win at Sandown Park on May 20.

While Immunity’s heat rivals include G3 Launching Pad winner Kuro Kismet (Box 7), Thompson is wary of Samantha Grenfell’s rails runner Nikoli Bale, a fast last start 25.59sec winner at Geelong.

“I think the hardest to beat might be the ‘red’,” he said.

“I’ve watched it closely and think he’s a really nice dog. He probably hasn’t won the races he should have but he’s been pretty unlucky.”

On Sunday night, Thompson is chasing another provincial feature at Sale, with the ultra-consistent Aussie Secret, winner of 19 from 40, lining up in the inaugural running of ‘The Horizon’ (440m).

Aussie Secret tasted defeat for the first time in five starts at Sale when runner-up to fastest qualifier Ferdinand Boy in last weekend’s heats and Thompson concedes it will be difficult to turn the tables on the Ballarat and Shepparton Cup winner.

“Aussie Secret is a very honest dog; he never runs poorly,” Thompson offered.

“He’s got a good record at Sale and certainly wasn’t disgraced last week.

“Ferdinand Boy is definitely the one to beat but I’m happy drawing on his outside this week rather than underneath him. Whether that will make any difference I’m not sure.

“We’re hoping but realistically if Ferdinand Boy leads, he wins and if Aussie Secret could run a place, we’d be rapt.”