The chapter discusses ways to make combinatorial auctions fair and efficient by modifying the VCG mechanism. These modifications are called second-chance mechanisms and ensure that participants are treated fairly and have the right incentives. The chapter also talks about how some VCG mechanisms can be too complex to compute efficiently, leading to poor economic outcomes. Different approaches are explored to address this issue, including non-VCG approximation mechanisms. Overall, the goal is to make combinatorial auctions work better for everyone involved.