Hail the RhinoBot. Unfortunately, one of the ingredients for this powerful physical trap is the Stale Super Brie.
For the more stoic hunters, they might actually find it hard to make Super Brie stale. That's because Super Brie cheeses are the well, creme la creme - the best attracting cheese for most mice, and the hardest to turn stale.
Well, except for these two locations:
Forbidden Grove and Acolyte Realms
Arm yourself with the Acronym and a stale effect base like the Explosive or the Aqua. Toss the Super Brie on it and watch it go grey-stale before your very eyes.
Be warned - do NOT leave your SB+ stash on the trap overnight - You literally harvest a Stale Super Brie with every blow of the Hunter's Horn. You only need 24 pieces for the RhinoBot, so it's going to be painful to overdo this.