In a nutshell, create a drip campaign that triggers when a contact is pulled into a custom list that collects members who match a specific deal stage.

In ActiveDEMAND:

Step 1

Create a single value picklist custom field on a contact that will hold a deal stage value. 

Administration->Account Settings->Custom Fields [Add Custom Field Type] 

Be sure to list the deal stage IDs in the options, one per line.

Step 2:

If you have not done so, set up a new import scheduler.

Contacts->CRM Contact Updates [New]

In your import scheduler, map deal stage to your custom field.

Step 3:

Set up a custom dynamic audience (list) that collects members based on your custom field (deal stage). (Contacts->Contact Lists)

Step 4:

Create a new drip campaign (Automation->Campaigns->Drip Campaign

Select the 'Added To List' option

Step 5:

Select your starting step, choose your list