What if Ohmwrecker built out of Bami's Cinder?
http://img2.wikia.nocookie.net/__cb20130710102757/leagueoflegends/images/6/6c/Ohmwrecker_item.png
Replace the Kindlegem with Bami's Cinder and have it deal 10 (+1 per champion level) magic damage.
Then have it so basic attacking a turret causes the passive to start effecting the turret and will ramp up in damage (To the turret) by 20% for each auto attack for a maximum of 100% increased damage. After 3 seconds of not auto attacking the turret, the passive will reset.
For balance purposed it could also be disabled if the user is damaged by an enemy champion.
Naturally numbers are subject to change but what do you think?