Avoid Critical Hit

 
Prerequisite(s): Dex 13+, Dodge, Skill Focus (Tumble), Base Attack Bonus 8+, Tumble 1+ ranks
 
Benefit: You can attempt to cancel any critical hit made against you. Note the modified attack roll that confirmed that a critical hit has been scored against you, and make a Tumble skill check. If your Tumble skill check result equals or exceeds the confirming roll (with modifications) then the critical hit is instead treated as a normal hit.
 
Source: Dragon Magazine #292