Add all of the rub seasonings to a small bowl and stir to combine.
Trim any large chunks of fat from the meat and trim the fat cap to around ⅛ to ¼-inch in thickness. Liberally coat the meat with rub on all sides and inside any crevices. If time allows, set it on a rimmed baking sheet and refrigerate overnight.
Preheat your smoker to 225°F. Place the pork butt in the smoker with the fat cap up and close the lid. Add wood chunks to your fire to produce the smoke, depending on your smoker.
This step is optional, but to speed up the cooking process, when the pork reaches around 150-160°F, remove the meat and wrap it tightly with foil or butcher's paper, then return it to the smoker. Raise the heat to 275°F. When the internal temperature reaches around 180°F, remove the wrap and return the meat to the smoker.
Continue cooking the pork until it reaches an internal temperature of 195-200°F, then remove it from the smoker. Wrap it in foil and let it rest for 30 minutes to an hour. After it has cooled slightly, shred the meat by pulling it apart with two forks or with shredding claws, then serve.