public function add_abilities($new_abbilities)
    {
        foreach ($new_abbilities as $abbility_str) {
            $camel = '';
            $abbility_str = str_replace(':', '', $abbility_str);
            foreach (explode('_', $abbility_str) as $str) {
                $camel .= ucfirst($str);
            }
            $class_name = 'PHPWarrior\Abilities\\' . $camel;
            $this->abilities[$abbility_str] = new $class_name($this);
        }
        return $this;
    }