Why does Darius's passive proc Black Cleaver's passive for free

I see. Thanks for the clarification.

Just found out the hard way.

Because the way the boards work is this:

If you ask a question on why something happens, it is automatically assumed that you are implying it shouldn't happen

It's fcked up but welcome to the boards

To answer your question, Darius's bleed applies physical damage multiple times over a series of "ticks". All cleaver needs is a form of physical damage to be dealt to a champion to start stacking, and so each individual tick of Darius's bleed stacks Cleaver because each individual tick causes physical damage

there's nothing harmless about sloppily written darius questions