Both of these Heroes have two different aspects to upgrade: both the hero level and the level of their abilities.
Heroes themselves are leveled up using Gold. By upgrading the Hero, not only will the Hero's health and damage increase, but also new abilities or new upgrade levels for said abilities may be unlocked.
Hero Token
Their abilities are upgraded using Hero Tokens, which can only be obtained through the Trader. By upgrading the Heroes' abilities, these abilities will be more powerful in battle. Owing to these upgrades, these abilities may do more damage, last longer, or generally become more effective.
The Hero Hut is similar to the Armory in the sense that only one hero or ability can be upgraded at a time. Both types of upgrades can be sped up using Diamonds.
Using Heroes in Battle
You may only pick one Hero to accompany your troops in battle.
While your chosen Hero may have three available active abilities, you may only select one of these abilities to use in battle.
While the Hero is deployed and not knocked-out, you may use the Hero's active ability by tapping the button in the center of the battle interface. Doing so requires Gunboat Energy. In a similar fashion to Gunboat Weaponry, each successive use of the ability will require more Gunboat Energy.
In addition to the chosen active ability, the Hero you choose will also have a passive ability, which activates automatically and does not require Gunboat Energy to use.
If your Hero's health reaches zero, she will be knocked out and will lie on the battlefield, stunned. The Hero will no longer participate in the remainder of the battle, meaning that you can no longer use her ability, and Defensive Buildings will no longer target her.
Once the battle ends, your Hero will be seen in the landing craft next to the Hero Hut, fully healed and ready for the next battle, regardless of her condition at the end of the previous battle.
Trivia
A unique Hero Landing Craft is berthed at the dock of the Hero Hut, which is used to deploy Heroes, and is deployed together with regular Landing Crafts. The numeral "01" on this Hero Landing Craft indicates its ability to hold only one Hero.
It is the only building found at your base that cannot be upgraded, only can be repaired.
There is a video by the actual Boom Beach channel showing a Royal Giant from Clash Royale as a hero, named G.I. Ant, shooting cannonballs from a distance. Video link [cP7bsA|here].
Heroes
Sgt. Brick After spending too long alone on the island, Sgt. Brick is ready to fight the Blackguard for real again.
Cpt. Everspark Some people just love gadgets. Cpt. Everspark takes after her mom, who has had a long career in weapons development.
