A prerequisite to getting started with this Workflow is to first set up Slack for Salesforce which can be found in the following Article.
With this Swantide Workflow, when a Picklist Field is set to a specific Picklist Value on Lead Create or Update, send a Slack Message to a designated Slack Channel.
Example:
In this example, my variable inputs are set to send a Slack Message to my Slack Workspace under the Channel #Inbound-Leads (Channel ID C05B5H08H5J) when a Lead is created or updated and Marketing Stage (Picklist Field) equals the value of "MQL"
I am able to retrieve my Workplace Id by opening Slack in a Browser Window which is highlighted in Red above. The Id with the starting prefix of "C0" is the Channel Id of my Slack Channel in scope.
I then proceed to select the Picklist Field on the Lead record by selecting the Field (Marketing Stage) then lastly selecting the Picklist Value "MQL"