Pat the drumsticks dry with paper towels to help the sauce stick. This step also helps the skin crisp a bit once the drumsticks are finished.
In a small bowl, whisk together the buffalo sauce, melted butter, garlic powder, onion powder, smoked paprika, salt, pepper, and cayenne (if using). This creates a well-balanced glaze with balance between heat, tang, and fat.
Place the drumsticks in the slow cooker, arranged in a single layer as much as possible. If needed, layer them in two rows to fit a 4-quart or larger slow cooker.
Pour the buffalo glaze over the drumsticks, then turn the cooker to low. Cook for 6 to 7 hours, or until the meat is tender and juicy and the internal temperature reaches about 165°F (74°C).
If your slow cooker doesn't have a tight lid or you want a stickier glaze, switch to the high setting for the last 15–20 minutes and let the sauce reduce a bit, watching carefully to avoid burning.
Carefully remove the drumsticks from the slow cooker and transfer to a serving platter. If you like a glaze that clings a little more, spoon any remaining sauce from the cooker over the drumsticks.
Serve immediately with your chosen dipping sauces. A dollop of ranch or blue cheese dressing on the side adds a cooling contrast to the heat, while celery sticks provide a crisp, refreshing crunch.