You bet win/loss on each matchup. Example: Bet 3 cards for Win on match X vs Y, bet 9 cards on Loss for match Z vs W, and so on...
this is example is correct. You do not have to bet on yourself to win. And you are only betting on your team's matches (so 6 bets in total), not ALL matches.
Obviously, the warmasters haven't learned from previous wars since they came out with this one right out of the gate. Do us all a favor and make '0' an option.
not gonna happen. Discards are only 9 this round and vaults are currently huge. If there was any time to use this card, it's round 1.
By betting the minimum, the worst case scenario is you suck at predicting and lose 18 cards (less than 5% of any vault) in addition to the cards gained/lost through salvage/discard. Best case scenario is you predict all 6 correctly and you gain 6 relics without losing additional cards.