Vendor Promotions add-on provides an option for vendors to create shopping cart rule with coupon (optional) from Vendor Portal. It enhances all the flexibility of Magento shipping cart rules.
On the checkout, promotions will apply to vendor's products only, leaving other vendor's products intact.

While creating a promotions, vendor will have the following options:

• Setup name and description
• coupon code (optional). if coupon code is setup, customer will be able to use it only after the code is submited on the checkout. If coupon code is not setup, promotion will be applied automatically
• Set the restriction on the number of times promotion could be used in general (Uses per Coupon) and/or by single customer (“Uses per Customer”)
• Set the dates when promotion will be valid From Date and To Date
• Apply - how promotion will effect customer shopping cart, i.e. how to use Discount Amount field. Options are:
  1. Percent of product price discount - subtract from product price percent
  2. Fixed amount discount - subtract fixed amount from each product
  3. Fixed amount discount for whole cart - subtract fixed amount for whole cart
  4. Buy X get Y free (discount amount is Y). In Discount Qty Step (Buy X) vendor need to setup how many same products customer need to purchase in order to get free items (Discount Amount in this case is number of free items)
• Vendor can restrict how many items are allowed to use promotions Maximum Qty Discount is Applied To
• Setup whether promotion will give customer Free Shipping and/or if Discount Amount can also affect shipping amount

This section allow to setup conditions that need to be met in order for promotion to be applied to customer's shopping cart.
Vendor can group sub-condiotions by logical unions. Setup conditions that check vendor products in cart as whole (total qty, total amount) or by existence (or not) of some products in cart (attributes check, categories check, by sku or combinations). Also address and shipping/payment method conditions.

This sections have a lot in common with Conditions section. Here the filter might be setup for which items it allows to apply promotions. Conditions section helps setup general rules and second rules by each product being checked.