Undead Slayer Feat 5
Source Pathfinder Advanced Player's Guide
Your knowledge of your own not-quite-living anatomy, combined with your experience in combat, helps you take down undead foes with ease. Against undead creatures, you gain a circumstance bonus to damage with weapons and unarmed attacks equal to the number of weapon damage dice for the Strike. This bonus increases to double the number of weapon damage dice if your target has the vampire trait.
Traits
Anything that doesn't list another rarity trait (uncommon, rare, or unique) automatically has the common trait. This rarity indicates that an ability, item, or spell is available to all players who meet the prerequisites for it. A creature of this rarity is generally known and can be summoned with the appropriate summon spell.
DhampirA creature with this trait is a member of the dhampir ancestry. These humanoids are the mortal offspring of vampires and members of other ancestries.