private function getFightNumberModifier(): int
    {
        $fightNumberModifier = 0;

        // strength effect
        $fightNumberModifier += $this->getFightNumberMalusByStrength();

        // skills effect
        $fightNumberModifier += $this->getFightNumberMalusBySkills();

        // combat actions effect
        $fightNumberModifier += $this->combatActions->getFightNumberModifier();

        return $fightNumberModifier;
    }