Place black beans into a large bowl and cover with several inches cool water; let soak 8 hours to overnight.
Drain and rinse beans thoroughly; place in a large pot. Cover with 1 inch of water; add lentils. Bring mixture to a boil; stir in roux mix until fully incorporated. Cover, reduce heat, and simmer until beans are tender, about 30 minutes.
Place diced bell pepper in a microwave-safe bowl; cook in the microwave until slightly tender, 30 to 60 seconds. Stir bell pepper, tomato soup, pumpkin puree, chili seasoning mix, sugar, cinnamon, nutmeg, cloves, and onion powder into bean mixture. Cover and simmer until flavors have blended, about 15 minutes, stirring occasionally.