This gem works similar to a Conduit Pylon, striking enemies and destructible objects within 40 yards of the character every second for the duration. The effect does not stack, only being renewed. Upgrading only increases the damage of each lightning bolt.
At rank 25, it also increases movement speed while active.
This gem is much weaker than a normal Conduit (which deals 4000% damage as Lightning per hit), but it does benefit from the Nephalem's Lightning skill damage bonuses. However, since the gem has a limited range, it will prove more useful to a melee hero. The chance to activate scales with the Proc Coefficient of each attack, and only triggers when the character lands a hit on an enemy, not when the character is hit.
Note that the damage indicated is NOT dealt to every enemy, but rather split among up to 5 enemies in range (chosen randomly): 5 lightning bolts hit every second, and may damage a single target with more than one bolt.
Wreath of Lightning
The madwoman Arianne believed she could cut a gem that would make for her a hood of lightning. "Lightning," she was heard to mutter "On my head!" Her body was discovered some weeks later, with no hair, clutching this gem.