Preheat your smoker to 325°F and just before you add the turkey, add two fist-sized chunks of mild smoke wood e.g. apple or cherry.
Spatchcock the turkey by cutting out the backbone then making a small cut along the breast bone. Flip the turkey so it is breast side up and press down so the bird is flat and spread out
Dry the turkey thoroughly with paper towels and then give both sides a few sprays of olive oil.
With the turkey breast side down, spread two tablespoons of the herb rub evenly over the whole underside.
Flip the bird and repeat the process, being sure to get some rub into all the crevices.
Use your fingers and a teaspoon to get some of the rub under the skin around the breast, pushing it down around the leg and thigh area. You can also slide a few fresh sage leaves under the skin.
Inject the turkey with the injection mixture in both breasts, drumstick, and thighs.
Place the turkey on the smoker breast side up and smoke at 300-325°F for one hour.
Use a basting brush drip the herb-flavored butter over the turkey
Keep smoking until the internal temperature of the breast reaches 165°F.
Remove turkey from the smoker and carve into portions.