User blog comment:Zilla4444/AP Version of Black Cleaver/@comment-186.136.186.166-20120726015034/@comment-5009341-20120728151359

10% cause there are so many 15% items, a usualy mage assassin gets dfg and has the sorcers masteies, in combination with this item the mage will have 29% cdr, so that if he finishes off with blue pot he will have 39%cdr

if i would increase the cdr i would have to increase the price, but this is a early game item, so it wouldnt be to useful

there are only 2 stacks, cause


 * 1) every stack reduce the mr by 12, but a squishy champ only has 30 mr by default, so with 3 stacks the enemy would have negative mr (bc also only reduces 45 armor out of atleast 60 (minimum armor of a champ))
 * 2) 2 stacks also cause many camps combo doesnt include more then 3 spells, so u need to make use of the mr reduction as early as possible, but 1 stack 24mrred would be OP, thats why 2