Well since rarity, level, and element of Your dragon are counted for this, I used my best army. But that doesn't mean if You're using the same dragon, You will get the same result. It's all about percentage, even You have 75% win, You could still lose at some point. If by any chance You're not worrying about silver coins, just fight them on with all You have...battling isn't cost that much anyway. But if You low on coins, have kind of mythic or any expensive habitat's dragon in the nest and couldn't afford to buy it, then don't battle. Sorry.