Preheat the oven to 375°F. Spread 1/2 cup of the 2 1/2 cups Green Enchilada Sauce in the bottom of a 9x13" casserole dish and set the dish aside.
In a large bowl, combine 3 cups shredded rotisserie chicken, the 4 oz can diced green chiles, 1 tsp cumin, 1 tsp garlic powder, 1/2 tsp salt, and 1/2 tsp onion powder. Stir until the chicken and chiles are evenly coated with the spices.
Warm the 8 large corn tortillas so they are pliable (for example: wrap in a damp paper towel and microwave 20–30 seconds or heat briefly in a dry skillet).
Divide the chicken mixture evenly among the 8 tortillas. Also divide the 8 tablespoons sour cream evenly among the tortillas (about 1 tablespoon per tortilla) and divide 1 1/2 cups of the 3 cups shredded Colby Jack or Monterey Jack cheese evenly to sprinkle inside the tortillas.
Place the filling near one edge of each tortilla, roll each tortilla tightly, and place them seam-side down in the prepared casserole dish.
Pour the remaining Green Enchilada Sauce (the rest of the 2 1/2 cups after the 1/2 cup used in step 1) over the rolled enchiladas so the tortillas are covered.
Sprinkle the remaining 1 1/2 cups shredded cheese evenly over the top of the enchiladas.
Bake uncovered at 375°F for 25 minutes, or until the center is heated through and the sauce is bubbly. Let the enchiladas rest for 5 minutes before serving.