I usually play twitch, and in a 5vs5 battle, my teammates usually enjoy the 5x12 armor reduction on at least 3 'enemy' champions. The spray and pray precision being what it is, it is usually difficult to land more than 5/6 shots before the opposite team starts to escape your shots. It is usually the warwicks, chogaths and yi who get the kills, and I'd rather leave the opposite team with a disadvantage on armor that my team can leverage on, than just getting 200hp more out of them.

I found that Black Cleaver was amazing during 5vs5 skirmishes, but that 1vs1 or BD situations would favour Infinity Edge; with its cold hard and immediate damage increase.

black cleaver gives 75 attack damage.

I Edge is for putting down squishy characters quick.

Black Cleaver is for cutting down tanks.

Both are really good items and work very well together or in conjunction with a champion that has the other.

Cleaver does not really work all that well on tanks w/ over 200 armor. At the max you will take off 60 armor with the cleaver which will take thier armor from 200 down to 140 which takes thier actual reduction percentage down to 58% from 66% which is netting not even an extra 10% in damage. I know there is more to the calculations that just the percent reduction, but I'm just saying that its passive isnt as great as it seems it may be.

I had a fantastic Armor Eating Taric game the other day, in which the Sunder Mastery (6 armor pen.) and a Brutalizer (15 armor pen.) paired with Black Cleaver (12 (x5 = 60) armor pen.) and Shatter (-30 armor in an AoE) gave me a whopping total of -111 armor after 5 attacks.

This game *does* support negative armor, too, thankfully, which equates into bonus damage.
I had a Fiddlesticks at ~ -56 armor, receiving an extra ~ 20% damage per hit.

Made Taric into quite the hard hitter, tbh.

We lost that game, due to some "extraneous circumstances" *cough someteammatesstillneededtolearntoplay cough* but it was hella fun none the less.

I solo'ed Warwick, and a rather fed one at that, both of us starting from full health, and came out quite soundly with about a quarter health.
Felt good.

Wanted to point out this is not quite right. Armor damage reduction percentage has diminishing returns for a reason, and thats because percentages don't work the way you're implying.

Say I do 100 base damage. With 66% mitigation, I do 34 damage. With 58% mitigation, I do 42 damage. This is actually a 23.5% increase in damage.

I'm not too familiar with the exact numbers from armor->damage reduction percent, but armor reduction is much more effective against tanks than you might think just subtracting percentages.

I play twitch usualy and I have a full runes book of all+ crit dmg equaling out to about 63% extra crit dmg with the 10% bonus from masteries included. ( im at work cant pull actual numbers) but I first get 5 avarice blades, my crit dmg bonus is so good i dont need +dmg early on. Then I get a BF sword then infinity edge... by then its 20-25 minutes in and i have 90% crit chance and deal 313% dmg off a crit. I now 3-4-5 shot people depending on the hero... tank take a couple more but meh.

My hero I combo with is Amumu. His Aoe stun with my ulti can kill the whole team in the span of the stun duration! I dont know how many penta kills i've gotten doing this.

Getting both is usually not an option in a higher end game. I used to get all the items I wanted every game, then my ELO got high enough that I usually run into good opposition and the games don't go beyond 45 minutes very often.

Black Cleaver is the better option on the majority of DPS heroes, IMO. Take it on Ashe over the Infinity Edge next time, you'll be surprised at the DPS boost. The armor you negate on the enemy hero helps a ton.

The biggest thing is that it's available at about 1000 gold cheaper, and is a significant boost in your damage output, meaning you can kill heroes and towers that much easier.