Dual Implement Spellcaster

Heroic Tier
Prerequisite: Dex 13, any arcane class
Benefit: When you use an arcane attack power and you are wielding a magic implement in each hand, you can add the off-hand implement’s enhancement bonus to damage rolls.
Both of your implements must be usable with this power, and you must be capable of wielding both implements, to gain this benefit.

Published in Arcane Power, page(s) 125.