Sunder

From DDO wiki

A sunder attempt is a melee special attack that, when successful, results in a -4 AC penalty to the target for 12 seconds if it fails a DC (10 + Str mod) Fortitude save. Some creatures may be immune to the sunder effect.. Only Fighters, barbarians, paladins and rangers receive this feat at level 1. All other classes receive it once their BAB is 1 (via leveling).

It has a 15 second cooldown.

Prerequisite: Base attack bonus of +1 or higher