Preheat oven to 250°F (121°C).

In a large bowl, combine cereals, nuts, and pretzels.

In a saucepan, melt butter over medium heat. Add corn syrup, honey, brown sugar, and granulated sugar. Stir and bring to a gentle boil for 3 minutes.

Remove from heat, stir in vanilla extract.

Pour the glaze over the cereal mixture, stir until evenly coated.

Spread the mixture on a baking sheet. Bake for 45 minutes, stirring every 15 minutes.

Cool completely, then serve or store in an airtight container.