Combine the dry base: In a large bowl, mix the cereal, pretzels, and peanuts so the salty crunch is distributed evenly before you add any chocolate.
Line a baking sheet: Line a large baking sheet with parchment paper so the mix won't stick once the chocolate sets.
Melt the white chocolate: Place the white chocolate wafers in a microwave-safe bowl and heat in 30-second bursts, stirring between each, until smooth and pourable, about 90 seconds total.
Coat the dry mix: Pour the melted chocolate over the cereal mixture and fold gently with a rubber spatula until every piece is lightly coated, not dripping.
Spread onto the sheet: Transfer the coated mix to the lined baking sheet and spread it into an even layer with the spatula.
Add the candy: Scatter the candy corn, candy-coated chocolate pieces, and mini marshmallows evenly over the top while the chocolate is still soft.
Finish with sprinkles: Sprinkle the orange and brown sprinkles over the mix for extra color before the chocolate firms up.
Let it set: Let the mix sit at room temperature until the chocolate hardens, about 15 minutes; a quick 5-minute trip to the fridge speeds this up.
Break into clusters: Once set, break the mix into bite-sized clusters with your hands, separating any large chunks.
Store or serve: Serve the mix right away in a large bowl, or transfer it to an airtight container to keep the crunch for up to 5 days.