Foe StoneLevel 12 Uncommon

This lodestone is set into a chain, and when aimed toward an enemy, it grants you understanding of your foes' weaknesses.

Wondrous Item        13,000 gp

Power (Minor Action)

Choose one creature you can see. You learn all the target's vulnerabilities, as well as which of its defenses is lowest.

Published in Adventurer's Vault, page(s) 172.