Talk:The Black Cleaver/@comment-8957269-20130430161514/@comment-6301771-20130507024732

It doesn't. Why would you even think it would? It's explained quite clearly that it only procs on physical damage, and Thresh's on-hit bonus doesn't deal physical damage. In fact, any physical damage on-hit effect still only applies the one stack, the damage is totally up and only applied once.

Draven's Wicked Blades procs TBC multiple times, as it deals physical damage over time. I've frequently used that as a harrassment tool.