Thundershield
First Post
As much as I hate disagreeing with you, Draco, this was elaborated in an earlier thread where a Swordmage asked if Dual Implement Spellcaster would allow him to apply the bonus from each end of a double-sword, and the responses from CustServ and the official FAQ were that it indeed was a legitimate combo as a double weapon in effect counts as two individual weapons/implements, but it needs to be a double weapon (or a staff wielded by someone with Staff Fighting).Dual Implement does not care about Twin Weapon fighting. Dual Implement does not care about that staff is a double weapon. Double Weapon does not make the staff into two implements.
The fact is, you're only wielding a single implement. Handedness does not apply to implements, which is why you can one-hand a staff for implement attacks.
However, as Rick and Dalzig already pointed out, it's hardly a superior combination. The bonus from the Staff of Ruin is an item bonus, which doesn't stack with other item boni (or itself, for that matter), and it's arguably cheaper to get an extra implement for your off-hand than burn a feat on getting proficiency with a double weapon or turning the staff into one, and getting a second implement also means you can have something with different properties and powers in your off-hand, but each to their own.
I'm more worried about the arcane casters picking Dual Implement Spellcaster and off-handing a Staff of Ruin for a +12 damage bonus to all their attacks as the Staff's property states that the item bonus applies whenever the staff's enhancement bonus does and the Dual Implement Spellcaster feat does indeed state that you get to add the enhancement bonus to damage. So far I've house-ruled that the Staff of Ruin's property only applies when the enhancement bonus is applied by normal means (i.e. main-handing it).