Preheat oven to 350°F (175°C) and line a baking sheet with parchment paper.
Slice the slider buns in half horizontally, keeping the rolls connected. Place the bottom half on the prepared baking sheet.
Layer the provolone cheese, beef pepperoni, beef salami, and sliced roast beef evenly across the bottom buns.
Place the top half of the buns over the meats and cheese.
In a small bowl, whisk together the melted butter, Italian seasoning, and garlic powder. Brush this mixture generously over the top buns.
Bake for 12-15 minutes until the cheese is melted and the tops are golden brown.
Remove from the oven. Carefully lift the top buns and evenly distribute the shredded lettuce, sliced tomatoes, red onions, and pickled pepper rings. Replace the tops, slice into 12 individual sliders, and serve warm.