Line a baking sheet with parchment paper.
Place 12 ounces chocolate candy wafers in a microwave-safe bowl and melt: heat 30 seconds, stir, then continue melting in 15 second intervals, stirring between each, until the chocolate is melted and smooth.
Pour the melted chocolate onto the prepared baking sheet and use a spoon to smooth it to a 1/4 inch thickness.
Arrange 12-15 pretzel sticks, 1/4 cup mini Oreo cookies, and 3 tablespoons Reese's Pieces over the chocolate, pressing each topping gently to adhere; scatter 2 tablespoons Halloween sprinkles with eyes and place the eye sprinkles individually as desired.
Place the baking sheet in the refrigerator for at least 10 minutes to set, then cut or break the bark into pieces.