Chex Legendary Muddy Buddies

Line large rimmed pan with waxed paper. In extra-large bowl, measure cereals and marshmallows; set aside. In 1-quart microwavable bowl, microwave chocolate chips, peanut butter and butter uncovered on High 30 seconds; stir. Microwave 15 seconds at a time, stirring after each, until mixture can be stirred smooth. Stir in vanilla. Pour over cereal mixture in bowl, stirring until evenly coated. Pour into 2-gallon resealable food-storage bag. Add powdered sugar. Seal bag; shake until well coated. Spread in pan to cool completely, about 20 minutes. Transfer cereal mixture to serving bowl; stir in pretzels, peanuts and candies. Store in airtight container.