Heroes are the strongest unit in the game, and they also cost no Mana to deploy. If your Hero dies, he/she can be spawned again after 30 seconds, albeit with minimum Hp. The only way to heal the Heroes is to retreat them to the Castle, then they will slowly regain lost Hp. All in all, it is much faster to let your Hero heal, than to wait for 30 seconds, and than heal (obviously). With all that said, you should really pay attention to your Hero Hp, retreat them when wounded, and avoid deploying Heroes that are low on Hp.
Each Hero has a unique special ability that provides some kind of a short-term buff, like increase attack and movement speed, reduce the damage taken for all friendly units within AoE, AoE stun, etc. For detailed information about Heroes and their special abilities, click on one of the Hero images above. Also, each Hero has a different base stats (Hp, damage, attack and movement speed).
Combination of special ability and base stats truly defines Heroes, and this is what makes some of them stand out in a certain role (offense, defense, early game rushing, etc.).
Since every Hero in Castle Burn has a unique play-style, I would recommend trying out every one of them for at least a few games, and with a different unit combination. Experimenting is the only way to find out something new, and by doing so, you’ll also discover that each Hero has a good synergy with a some, but not all units. So, for example, you might find that the Archers work better with Leon than with Aela or that the Goblins work better with Aela than Leon, etc. After trying out all of them, you’ll probably find your new favorite Hero.
Hero Levels and Tiers
You can upgrade the level of your Hero the same way that you can upgrade units, that is by having multiple cards of the same Hero. Level 2 requires 2 Hero cards and every additional level will require approximately twice as many cards as the previous one. Each time you upgrade a Hero, his/her damage and Hp will be increased by 10%.
Hero Tier is directly connected to Castle Tier. So, when you upgrade your Castle to Tier 2, your Hero will automatically become Tier 2. When Heroes advance to Tier 2 their Hp and damage stats will be increased by approximately 30%, which is a significant amount. To view Hero stats at different Tiers tap details button on the Hero card.