There are three hero units for your home village: Barbarian King (unlocked at town hall level 7), Archer Queen (unlocked at town hall level 9), and Grand Warden (unlocked at town hall level 11). The sole hero for your builder base army is Battle Machine (unlocked at builder hall level 5).
To gain access to heroes, construct the building associated with the specific hero. These units are immortal, meaning they only need to rest to recover any health lost during battle. Heroes will defend your base against attacks unless you set their mode to Sleep. If you have plans for a hero at a certain time, set them to Sleep so they remain available.
Barbarian King
Barbarian King is the ultimate tanking unit when deployed to attack. Support the Barbarian King with ranged units and healers to get the most out of him. On defense, set up his altar in the middle of important buildings. He won’t stray far from his altar, so the attacker can’t lure him away from your other defenses. His special ability is Iron Fist, which acts like a personalized Rage Spell (the two won’t stack) and summons a temporary force of barbarian troops.
Archer Queen
Just as her name implies, Archer Queen wields a bow with greater power and range than the archer troops produced by the barracks. If you employ her in attacks, she should be in the third row of a coordinated group. The lead group is melee units and tanks, with ranged attack units set up behind them. The Archer Queen’s greater range allows her to set up behind the other ranged units, keeping her protected from return fire. She’s fantastic on defense due to her range and ability to hit both ground and air units. Keep her altar well behind the walls or she might leave their protection to continue hitting invaders. Royal Cloak, the Archer Queen’s special ability, makes her invisible to enemy units and summons archers.
Grand Warden
Grand Warden is a support hero that operates in ground mode or air mode. While he does his part during attacks to deal damage, his true value is in his Life Aura, which is a passive ability that boosts the health of nearby friendly units. His active ability is Eternal Tome, which briefly changes the health bonus to invulnerability. Choose air mode for your Grand Warden if he’ll be supported by other air units. If he’s the only target for air defenses, he won’t survive for long.
Battle Machine
Master Builder outdid himself with Battle Machine, a barrel-themed suit that wields a hammer to great effect. While Battle Machine primarily acts as a tank that allows ranged units to do their work safely, its Electric Hammer ability allows it to join in on base destruction. Each activation boosts the damage for three swings. Save Electric Hammer for buildings that have either high damage output or a large pool of hit points.