Melt 8 tablespoons butter in a microwave-safe bowl.
Add 2 teaspoons Worcestershire sauce, 1 teaspoon seasoned salt, ½ teaspoon garlic powder, and ½ teaspoon onion powder. Whisk until well combined.
In a large bowl, combine 2 cups Rice Chex cereal, 2 cups Corn Chex cereal, 2 cups Wheat Chex cereal, ¾ cup mini pretzels, ¾ cup mixed nuts, and ¾ cup cashews.
Pour butter mixture over cereal mixture and mix until well coated.
Spread evenly onto cookie sheet.
Bake for 30-40 minutes, stirring halfway in between.