In Olden Era, the mechanics also affects the classic three heroes, e.g. it does not directly increase the damage or protection from unit heroes, but it works like this: 

• Attack from 10 mechanics with attack 8
• Hero with defense 15
• Attacked unit minotaur with shield 20

The defense is subtracted from the hero's defense and is 23, further subtracted from the shield of the attacked unit 20 its attack +3. 

Further, the damage increases by the hero, if it is positive, then the defense increases by 5% for each point, and if the shield of the attacked unit was larger than the attack, then the overall defense increases by 2.5% for each point. 

In our case, the attack is higher than the shield by 3, in defense 8 units with attack 8, i.e. base defense 80, but we add 15%, so as a result, the attack is higher than the protection. And it turns out that the resulting defense by minotaur will be 80 +15% = 92. 

Naturally, the more defense and its base defense then the more will be the final effect from the hero's characteristics.