Preheat the oven to 350°F (175°C).
In a mixing bowl, combine the black beans, corn, cheddar cheese, Monterey Jack cheese, cumin, chili powder, garlic powder, and salt. Mix well.
Spread 1/4 cup of the enchilada sauce evenly on the bottom of a 9x13-inch baking dish.
Warm the corn tortillas in a dry skillet over medium heat for about 30 seconds on each side, or until they are pliable.
Spoon about 1/4 cup of the bean and cheese mixture onto each tortilla, roll them up tightly, and place them seam-side down in the baking dish.
Once all the tortillas are filled and in the dish, pour the remaining enchilada sauce over the top, ensuring all the tortillas are covered.
Sprinkle any remaining cheese on top of the enchiladas.
Cover the baking dish with aluminum foil and bake for 20 minutes. Remove the foil and bake for an additional 10 minutes, or until the cheese is bubbly and slightly golden.
Let the enchiladas cool for a few minutes before serving. Garnish with fresh cilantro and serve with sour cream if desired.