In my case, I was able to install OS Monitor and then watch the Messages tab.
When I started up TWD:RTS, I started getting thousands of errors related to media players and codecs. At the same time I could watch the mediaserver using up more and more battery.
try downloading "adware" it's pretty neat and tells you what types of adware are associated with each app. I think adware only detected the ad once I scanned shortly after it showed up so you might need to scan with adware right away too. Here's a link to adware
it's for android
https://play.google.com/store/apps/details?id=com.keerby.adaware&hl=en