Preheat oven to 350°F (175°C). Lightly grease a 9x13-inch baking dish.
In a large skillet, cook ground beef over medium heat until browned. Drain excess fat.
Add taco seasoning and water to the beef. Simmer for 5 minutes until thickened.
Stir in black beans and diced tomatoes with green chiles. Heat through.
Spread half the corn chips in the bottom of the prepared baking dish.
Top with half the beef mixture and 1 cup of shredded cheese. Repeat layers with remaining chips, beef mixture, and cheese.
Cover with foil and bake for 20 minutes. Remove foil and bake for 5 more minutes until cheese is melted and bubbly.
Meanwhile, mix sour cream, ranch dressing mix, and hot sauce in a small bowl.
Drizzle spicy ranch over casserole and garnish with fresh cilantro before serving.