This crystalline silver gem glows when you have advantage over your foes.
Enhancement Bonus: attack rolls and damage rolls
Critical: +1d6 damage per plus, or +1d10 damage per plus if you have combat advantage
Power Daily (Free Action)
Trigger: You hit a target that is granting combat advantage to you.
Effect: You deal 2d6 extra damage to that target.
Published in Seekers of the Ashen Crown, page(s) 24.