Battle Wager

Battle Wager is a feature of Legends' Championship where players can gamble with their gold by predicting the winner of incoming Legends' Championship matches. The amount of gold available for wager is 48 hours of your AFK rewards chest production while the prize increases while you progress in the campaign.

Betting is a decent way to earn (or lose!) extra gold, sometimes the winner can be determined easily, but most of the time matches and hero rosters are quite close. Things to look out for while betting are:

Ascension levels of heroes in the roster (the higher ascension, the better)
Faction bonus in teams (the bigger the bonus, the better)
Team compositions
Look for well-known players (but don't depend solely on that, they can lose too!)

Each championship lets you wager 6 times. Each match takes place around 12:00 UTC on subsequent days. You can check your betting history and gold balance under the stats button in the wager menu.