Measure. Measure cereal into a very large bowl and set it aside.
Make coating. In a microwavable bowl, microwave chocolate chips, peanut butter, and butter for 90 seconds, stirring halfway through. Pour mixture over cereal, stirring well until evenly coated.
Add sugar. Measure powdered sugar into a very large (2 gallon or larger) plastic bag, add coated cereal, and shake until well coated. Spread on waxed paper to cool.
Combine. Add animal crackers and candy to coated cereal and shake again. Serve in a clean bowl or directly out of the bag.
Notes
Don't have a 2-gallon bag? Just split the cereal roughly in half for the shaking portion.