Talk:Armor penetration/@comment-173.18.158.250-20120222043644/@comment-4087140-20120222044816

The Ancient Golem has 20 armor. reduces armor by 15 per hit, and that's what allowed you to do bonus damage (which ends up being +28.6% once all four stacks are on). Armor reduction can bring armor below 0; armor penetration (all the rest of your stuff) cannot.