With this new addition, you can now set "triggers" for when your device charges or drains to a certain battery percentage level. For instance, you could have your iOS device play a ringtone when it reaches a certain battery level, or a warning sound when it drops to another level.
To access the new feature, you simply go to Activator through your settings app, tap Anywhere, then the Edit button in the top right. From there you will see both the option to set percentages for battery drains or battery charges.
The new version of Activator is a beta, but you can get early access to it by adding Ryan's beta repo: rpetri.ch/repo. Some have reported the new feature does not always work properly, so you might want to wait until its official release.