In a saucepan, melt the unsalted butter over low heat.
Once melted, remove the saucepan from heat.
Stir in the chopped rosemary, thyme, sage, garlic powder, onion powder, black pepper, and salt. Mix well to combine.
Add the chicken broth into the mixture and stir until fully integrated.
Let the marinade cool for about 10 minutes, then strain through a fine mesh strainer into a mixing bowl to remove the herbs, ensuring a smooth liquid for injection.
Using the injector syringe, draw the marinade into the syringe.
In an adequately thawed turkey, inject the marinade into different parts of the turkey, such as the breast, thighs, and legs, aiming for even distribution. Use about 1 cup of marinade for a 12-14 pound turkey.
Allow the turkey to rest for at least 30 minutes (or refrigerate if preparing ahead) to let the flavors penetrate.
Cook the turkey as desired (roast, grill, or smoke) according to your preferred method and cooking time.