Just like defenders, they share the Hero's main weapon. They will also spawn with the hero's current max HP and attack. Attackers form the King's Regiment.
Every units defeated by an attacker will grant 5 times more gold than a regular unit. They do not grant gold to the enemy upon death.
They will always critical hit the enemy king and the damage they receive from him will be halved.
Five of them are automatically summoned after 20 of your units have been defeated by an enemy king. Attackers' summon gauge is visible under King's health bar.