What is more important: luck or fighting spirit?

Here's an example... 50 blessed harpies attack five black knights with luck, either once or twice in a row.
In the first case, they will deal maximum damage with a double strike (200%)...

Luck ignores the presence of a secondary "attack" skill in the hero. It also ignores the attack superiority over defense; however, if the defending monster's defense is higher than the attacking monster's attack, this is taken into account when calculating the additional damage from luck, and in some cases, the damage can even be slightly more than 200%.