Shield of Siberys
( Dragonmarked, p. 144)[General]
Your dragonmark protects you against the powers of those cursed with aberrant dragonmarks.
Prerequisite
Any true dragonmark,
Benefit
If a creature with an aberrant dragonmark comes within 60 feet of you, you can sense its presence (though not its exact location).
In addition, you gain spell resistance equal to 15 + your level in the heir of Siberys prestige class (if any) against the spell-like abilities of aberrant dragonmarks.