The free plugin covers percentage, fixed, and fixed price discounts, quantity tiers, cart discounts, role pricing, and same product BOGO. Pro adds the discount types that need a bit more.
Cross product Buy X Get Y, for example buy a camera and get a memory card free
Free gift products added to the cart when a condition is met
Product bundles priced as a set
“Spend X more to save” messages that nudge shoppers toward the next threshold