Mix the first five ingredients (cereals, nuts and pretzels) in a microwavable bowl and set aside.
In a small microwavable bowl, add butter and heat it in a microwave for 30-40 seconds until melted. Add brown sugar, salt and chilli powder and mix well.Pour over the cereal mixture and mix until evenly coated.
Microwave the mixture uncovered in a HIGH setting for 4-5 minutes. Make sure you stir every two minutes.
Spread on paper towels to cool for approximately 10 minutes.