Mix paprika, garlic powder, black pepper, sea salt, and cayenne pepper in a bowl until thoroughly combined. Set spice mixture aside.
Heat olive oil in a large skillet over medium heat; cook and stir mushrooms and shallots until mushrooms have released their liquid, 5 to 8 minutes. Set mushroom mixture aside.
Melt 1/4 cup margarine in a large skillet over medium-high heat and stir in 1/4 cup Worcestershire sauce. Rub beef brisket thoroughly with spice mixture; place brisket into the margarine and Worcestershire sauce.
Brown the brisket well on all sides, about 5 minutes per side. As the Worcestershire sauce cooks into the brisket, pour in more, about 1/2 cup at a time, until 1 1/2 cup Worcestershire sauce has been added.
Place a rack into a heavy Dutch oven; place the brisket onto the rack. Pour in the Worcestershire sauce pan drippings, red wine, water, garlic, and beef broth. Top the brisket with the mushroom mixture. Drizzle 1 tablespoon Worcestershire sauce over the mushrooms and top with 2 tablespoons sliced unsalted margarine.
Cover the Dutch oven and bake brisket in the preheated oven for 3 hours. Reduce heat to 300 degrees F (150 degrees C) and bake 1 more hour. Reduce oven temperature to 225 degrees F (105 degrees C) and bake 1 additional hour. Baste with pan drippings every hour.
Let the brisket rest for about 20 minutes before slicing thinly across the grain. Serve with pan gravy.
