Login Security Solution is a very useful plugin if you want to slow down brute force attacks, enforce password policies and timeout inactive sessions. It is also worth mentioning that it records the IP address of every failed login attempt so it is easy to integrate with your own solutions such as htaccess deny directive.
To display top ten offending IP addresses for the current month execute SQL query:
SELECT ip, COUNT(ip) AS COUNT FROM wp_login_security_solution_fail WHERE YEAR(date_failed) = YEAR(CURDATE()) AND MONTH(date_failed) = MONTH(CURDATE()) GROUP BY ip ORDER BY COUNT DESC LIMIT 10
Modify the above SQL query to get something more specific than just a number of failed login attempts for current month grouped by IP address so you can use the obtained data to update htaccess file using deny directive or anything else that comes to your mind.