The alarm clock pull the data of Voting Gauntlet and ring when your selected character is 10% or more behind your opponent.
Known bug :
(Fixed) - The UI keep reset back to default state after close and re-open the app. However, if you already set the alarm up, it will remember your set up before closing the app fine. You can confirm you're still good by looking at "Alarm Status ON" right after open the app. It's the only thing that does not reset to default state. I'll address this bug on next update (too many people complaining about this bug).