Ghoul Sores is a Creature research item in Dragon Age: Inquisition.
Acquisition
Looted from Ghouls.
Usage
Return this item to the research table and once sufficient research has been carried out, a permanent damage bonus to undead will be granted.
Bugs
When sufficient research has been carried out, the Codex updates with "Researched: Damage Against Darkspawn Increased"; however the notification, which appears above the mini-map, states "Damage bonus against undead."