There is an app on the Google play store called "Floating Counter" it can be used for keeping track of encounters. It is very easy to use. When you first install the app and open it should look something  like this (the first uploaded image) you can customize each card by holding it for a few seconds to highlight it and selecting the pencil icon at the top of the screen (refer to image 2) from there it is pretty straight forward for editing. After you are done customizing press the save icon. Yo