When your attacks catch foes off guard, you place a magical mark upon them which makes your attacks more deadly.
Benefit: When you successfully deal sneak attack damage to an opponent, that opponent becomes marked by your arcane mark for a number of rounds equal to the number of dice you possess in sneak attack. When you attack an opponent who has been marked in this way, your weapon bypasses any damage reduction that your opponent possesses and your critical threat multiplier increases by 1 (e.g., from x2 to x3). You may only mark each individual opponent in this manner once per day, and this use of arcane mark does count against the number of times you may cast the spell per day (if applicable).
Undefeatable: The Collected Feats Sourcebook, Copyright 2009 – 2010, Louis Porter Jr. Design, Inc. Undefeated, Copyright 2011, Louis Porter Jr. Design, Inc.