@flyweed
A few examples of presence sensor use:
1) Rule: If smartphone inactive, then set home mode to away
2) Rule: If smartphone active, then set home mode to home
3) Rule: If Amazon Dash button active and light is off, then turn light on
Note, it is more difficult to reuse something like an Amazon Dash button for multiple things. For example, if you create another rule similar to #3 above.
4) Rule: If Amazon Dash button active and light is on, then turn light off
This rule would "overlap" with #3 and it would cause erratic behavior as one turns on the light and one turns it off, until the button goes inactive.