Preheat the oven to 375 degrees F (190 degrees C).
Brown ground turkey in a skillet over medium heat, breaking it up into crumbles as it cooks, about 10 minutes. Stir in taco seasoning mix and water, bring the mixture to a boil, and reduce heat to low. Simmer turkey mixture until thickened, about 5 minutes. Stir in chopped green chilies and remove from heat.
Spread a scant 2/3 cup enchilada sauce evenly over the bottom of an 8x10-inch baking dish; top sauce with 4 tortillas, overlapping if necessary. Spread tortillas with half the sour cream, half the refried beans, half the turkey mixture, and 1/3 the cheese blend. Top with another 2/3 cup enchilada sauce and 4 more tortillas. Firmly press down on tortillas to compact the layers beneath.
Repeat layers, spreading remaining sour cream, refried beans, turkey mixture, 1/3 the cheese blend and 2/3 cup enchilada sauce onto tortillas. Top with remaining 4 tortillas; press down as before. Finish layering casserole with remaining 2/3 cup enchilada sauce and remaining 1/3 the cheese blend.
Bake casserole uncovered in the preheated oven until the cheese topping is melted and bubbling and casserole is hot, about 20 minutes.