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**BerserkRequiem**:

. . . What does that mean you might ask. Well it means if you have a black cleaver, you apply up to 4 stacks taking 30% of your enemies armor+ 20 armor pen after that fact. If you have 2 black cleavers. Each one of them can stack up to 4 times. For a total of 2x30% armor shred+ 40 armor pen even more hp and 20% CDR. While the health and armor pen are nice losing 60% of your armor pretty ****ing much hurts bad. So between masteries ( 6|8% penetration) You then add in 40 pen and 60% armor shred. . . . Wanna take a gander at what happens with 3 Cleavers? 90% shred 8% pen and 45 flat pen. You push people into the negatives.

First, no; you don't get 60% armor shred with 2 cleavers, you get the same 30% shred as with one, but you get there twice as fast; that's all - and you get double the flat pen. The tip on BC specifically states that the shred maxes out at 30%, this is the same terminology as before with max stacks, it's the same as other items & passives that have "max" stacks.

So your example with 200 AR mumu sees you getting through 100 armor with 2 cleavers and no runes or masteries. 4 Cleavers will get you through 140 armor leaving 60, if you have no masteries. If Amumu foregoes that 100 armor item, or just makes it an Omen, you still have to deal with his 3000 hit points; 4000 if he gets a Warmogs; 5000 if he gets 2 - they're much cheaper than cleavers. What good is 300 AD and 30% +80 arpen against that? (while he's eating away 10% of everyone's health every second [all damage included]?) Note that your carry only gets the 30% shred, still having to deal with 140 of the rest of Amumu's armor, and 5000 hit points (effective 12k).

EDIT: Finally, no, penetration doesn't

*reduce* armor, so even if 3 cleavers gave you 90%, and that 90% stacked

*additively* (it stacks multaplicitavely) with the 8%, that still only would reduce 90%, the pen meaning

**you** (and only you) would get up to 100% arpen. If you had 4 cleavers and these were true, you'd only shred 100% armor, because % shred

**can't** reduce armor below 0 - you'd need flat shred to do that, and there are only ~ 5 champs out of 100+ who can do that. However, 1) cleavers max out at 30%, 2) % shred and pen stack multaplicatively, so 35% pen from LW, and 8% pen from masteries, is equal to 1 - (.65 x .92) = 40% pen, not 43% pen. If cleavers stacked that would be 1 - (.7 x .7 x .7 x .7) = 76% shred, not 120% => 100%. Combined with even the 40% pen above would be 85.5% effective pen (and that only for you). By the way, % pen & shred scale multiplicatively because % pen goes off of what's left, not what was originally there.