public static function forge($custom = array())
	{
		// Driver is given as array key or just string in custom
		$custom = ! is_array($custom) ? array('driver' => $custom) : $custom;
		$config = \Config::get('auth.'.$custom['driver'].'_config', array());
		$config = array_merge($config, $custom);

		// Driver must be set
		if (empty($config['driver']) || ! is_string($config['driver']))
		{
			throw new \AuthException('No auth driver given.');
		}

		// determine the driver to load
		$driver = \Auth_Login_Driver::forge($config);

		// get the driver's cookie name
		$id = $driver->get_id();

		// do we already have a driver instance for this cookie?
		if (isset(static::$_instances[$id]))
		{
			// if so, they must be using the same driver class!
			$class = get_class($driver);
			if ( ! static::$_instances[$id] instanceof $class)
			{
				throw new \AuthException('You can not instantiate two different login drivers using the same id "'.$id.'"');
			}
		}
		else
		{
			// store this instance
			static::$_instances[$id] = $driver;
		}

		// If we have more then one driver instance, check if we need concurrency
		if (count(static::$_instances) > 1)
		{
			// Whether to allow multiple drivers of any type, defaults to not allowed
			static::$_verify_multiple = \Config::get('auth.verify_multiple_logins', false);
		}

		return static::$_instances[$id];
	}