1. Coverfire is 5% of your top 5 ATT and DEF not currently in your lineup. If you have 10 Water Bearer Livonah's not in your lineup, it will be 5% of their attack for each of them considering you do not have anyone with higher attack in reserves.
2. Cannons are extremely valuable as they can make or break an offense or defense. Although Water Bearer Livonah has extremely high attack for the cost that she consumes, she also takes away 2 cannons from your ATT every time her skill triggers. So if you have 5 Livonah's and all 5 of them trigger, that is -10 cannons from your ATT giving you a very crappy chance of defeating decent defense.
3. The people that are ranked high in the daily brawl rankings do 1 of a few things. They either use 3 very hard hitting attackers, and use 2 pixies or something so they do not utilize all of their ATT at once giving them the ability to attack multiple times without using kraken jugs and still earning wins, or they put their hardest hitters in to ensure a victory and rake up a few extra brawl points for overkill while using quite a lot of kraken jugs.
4. Currently, all bosses after chapter 8 in any nation do not give the correct cards when using persuade. The mods are working on looking into this, but at the moment, they all give cards other than what they are supposed to. If for some reason you get a card which is not the correct card used when trying to persuade, send in a ticket to Aeria Mobile, and include a screen shot. They are usually very prompt about issuing the correct cards.
5. The max combo level is set at 200. As long as you feed it, the combo lvl will rise. The higher the combo lvl, the more likely your pirate will utilize it's skill, and pair up with another pirate for a saucy combo.