How do I create discounts that require multiple items?

I'm looking to create more sophisticated discount strategies that encourage customers to purchase multiple items or reach specific cart thresholds. My current discount approach feels too simplistic, and I want to design promotions that not only incentivize larger purchases but also help me move specific inventory or increase average order value. I need a comprehensive understanding of how to set up multi-item discounts, what rules I can implement, and how to make these promotions attractive to customers without sacrificing my profit margins.