All apps have a feature that makes all the difference from all the others in the market. Therefore it is critical that the highest number of users know about and use that feature.
When you use Liquid's Formulas, you'll select the audience, the action and the time.
Users who never used a specific feature
Send a Push-Notification highlighting the benefits of that feature
Send it next day at the time the user usually uses the app
Define a custom segment with users that never used a specific feature.
Select Push-notification as the action and write a message that highlights what the user benefits by using the feature. Also, setup a deep linking that takes the user directly to the feature page in the app.
Schedule the time for the next day and select the “Send at the optimal time” option.