Combine tomatoes, salsa, tomato paste, black beans, corn, chilies, cumin, and garlic powder in a bowl and mix.
Put 1 cup of mixed ingredients into the bottom of a slow cooker on low heat.
Spread evenly and top with 1/2 of tortillas, cutting to fit pot.
Spread 1/3 of remaining ingredients over top and add the rest of the tortillas in the same fashion.
Cover and cook about 5 hours.