Heat oven to 375°F. Lightly oil a 9x13-inch baking dish.
Warm olive oil in a large skillet over medium heat. Sauté onion until softened, 4–5 minutes.
Stir in cumin, chili powder, garlic powder, salt, and pepper. Cook 30 seconds until fragrant.
Add green chiles, corn, black beans, and shredded chicken. Toss to combine and warm through.
Pour in 1 cup enchilada sauce. Simmer 1 minute to coat, then remove from heat.
Spread 1/2 cup enchilada sauce in the baking dish. Arrange tortillas to cover the bottom, trimming as needed.
Spoon half the chicken mixture over tortillas. Sprinkle about 1 cup cheese and drizzle 1/2 cup sauce.
Repeat layers. Top with remaining tortillas, the rest of the sauce, and remaining cheese.
Cover with foil and bake 20 minutes. Uncover and bake 10–12 minutes until bubbly and lightly browned. Rest 10 minutes, then garnish with cilantro.