Umbral Mark

(Dragonmarked, page 144, DnD 3.5)

[General]

Your dragonmark grants you new insight into the ways of shadow, making it harder for opponents to critically wound you.

Prerequisite

Any Mark of Shadow

Benefit

Once per day, you can reroll any one Hide check. The decision to reroll must be made before learning the outcome of the original roll, and you must accept the result of the second roll. In addition, any critical hit or sneak attack made against you has a chance to be negated so that damage is instead rolled normally. The chance depends on the strength of your dragonmark.

Special

The benefits of this feat do not stack with any other effect that grants a percentage chance to negate extra damage from a critical hit or sneak attack.