Combine flours, butter, salt, and cheddar in a food processor. Pulse until salt and cheddar become small chunks. Add ice water while the food processor is running until a dough forms. Form dough into a disc, cover with plastic wrap, and chill for 1 hour or overnight.
Preheat oven to 350 degrees F. Line 2 baking sheets with parchment paper.
Dust a clean work surface with flour. Roll out dough into a 1/16-inch thick square and cut into 1x1 inch squares. Poke a hole in the center of each square with a skewer. Transfer to baking sheet and bake for 12-15 minutes or until crackers are lightly puffed and golden browned. Remove and let cool completely.
In a small bowl, combine melted butter with garlic powder, seasoned salt, chili powder, and cayenne.
Toss cheez-its with pretzels, Chex, and oyster crackers. Pour seasoning butter over crackers and toss to coat. Microwave in a microwave-safe bowl for 3 minutes, tossing every minute. Spread the party mix in an even layer on parchment paper and let cool. Serve.