Originally Posted by wildfire393
Gatling does NOT apply on-hits (it'd be busted with stuff like Madred's if this was the case). However, you can autoattack while it's going on. So applying massive armor reduction via gatling and then even more massive reduction via black cleaver = they have negative armor and are taking extra damage, which leads to them dying quickly.
Sorry, I used to play him alot and rush black cleaver for the added armor pen, though I misinterpreted my old build and was thinking it was automatically applied it. I forgot that it had to be manually applied, which is still very effective as you mentioned.
Eitherway, my old build revolved around high damage output with Black cleaver, Bloodthirster, Frozen Mallet (I think) and Infinity edge if possible. Depending on the game, this leaves you free to get 1 armor or survivability item of any kind, or two if you drop one of the items I listed (given they are all high cost items). Boots depend on the game, just remember to try to keep Valkyrie off CD for the escape, and attack speed is not necessary when you have his gatling gun. Late game you'd be a fool to stand in it.