Zen Cart Combination Discounts builds on the discounting mechanism introduced in Better Together, allowing you to create linkages between 3, 4 or more categories or items for the purpose of discounting. Note that Combination Discounts comes in two variants: Combination Discounts or Combination Discounts with Buy The Set. For more information, please see Combination Discounts World.
Combination Discounts was an early effort to extend Better Together so that offers involving more than two products could be created. If you are willing to sacrifice a little flexibility (a limit of 12 on the number of condition and discount items), then Discount Chooser could be a better option for you.