Here is a documentation of the new Slack app.
Getting started with Slack
To get started with Slack, you need to connect your Slack.com account to Integromat.
Connecting the Slack service to Integromat
To connect your Slack account to Integromat, follow the general instructions for Connecting to services. After you click the Continue button, Integromat will redirect you to the Slack.com website where you will be prompted to grant Integromat access to your account:
Here, allow access by clicking the Authorize button. Afterward, you will be redirected back to the Integromat administration page. Now, you can continue creating your scenario.
Slack offers a wide range of text formatting options. For more information, please refer to the Slack API Documentation.