I posted this in a previous thread and realized that it could be helpful. I have only theorized this and crunched mathematics on this idea but I believe it will work for people who are frustrated with BC stackers. (Note: this does not reflect rune pages or masteries)

"Just build frozen heart and randuins are enough to counter the BC... FH passive reduces Attack Speed from of surrounding champs by 20% while randuins will reduce their Attacks speed a further 20% when they AA you..While a champ with multiple BC will reduce your armor their DPS will be much much lower... and since they have no damage you can effectively kill them in a fight situation.

FYI thats 160 armor... with 4 BC thats still only reduces you to 112 armor... and after the flat reduction reduces you to 52 armor... far from true damage... now lets say just to counter them you even got

Ninja Tabi (or any boots for that matter), 2 BC yourself and those two armor items and something as simple as a BT... you'd be demolishing them...because A) they have no real defense...besides health B) they wont out DPS you because C) The health from randuins effectively gives you the same health as the 2 additional BC. D) Frozen Heart gives you just as much cool down reduction as the two additional BC...

So now you effective have just as much CDR and Health as the person with 4 BC... more armor... there is no reason you should not win in this match up... heck the AS debuff may even make your AS faster than theirs... and yet you now have more effective health...!!"

Attack speed reduction does not affect Riven's Broken Wings, Garen's Judgement, Pantheon's Heartseeker Strike, or Talon's Rake, which are all the main abilities people are complaining about in regards to Black Cleaver. None of these champions honestly even rely on attack speed, so it isn't as much of a counter as you may think; also, only tanks would conceivably spend the money for these items, so that still leaves the rest of the team to eat the cleavers.

But bruisers on the other hand... I get where you are coming from but the bottom line is those abilities still go on CD and must rely on AA until then...Now with 40% cdr they can use them much more often... but they still go on CD bottom line... with my suggested build you have the same CDR as someone stacking 4 and just as much health, more armor, more dmg overall. especially an AD champ.. and last but not least Life steal. You will out sustain them... even with some of their burstyness.. Im not saying this is a genuine all round wait to counter it but if you are a ad top its another story.

Randuin's Omen by itself counters 2 Black Cleavers HARD.

You get 500 health, 70 armor, and a SWEET active.

This is completely ignoring the defensive slow of the item.

It should also be noted that the 40% (or is it only 35%?) AS slow is directed at carries, not 4-cleaver noobs - they can be ignored 'cause they have a whopping 1k damage (and you have a whopping 3k+ hp) every . . . 20 - 40 seconds (whatever it is, it's still not as important as the carry's continuous damage).