Originally Posted by Zenmetsu Saseru
You can use it on AD casters, but it would take somewhat longer to apply the full reduction. That aside, AD caster's output is by their abilities, which would give stacks, but wouldn't be as effective as someone who doesn't spend resources for their damage and have to wait to take advantage of the reduction. As a AD caster, you should wait for your friend to apply the reduction so you can lay out the damage unhindered and you can also have that slot free for something else.
im sorry but ad casters are the ones that apply the stacks the fastest.
most ad casters will have such low cooldowns that with the increased cooldown reduction, you'll get more damage out of this than anyone else
also the passive shred is not unique, but the debuff can only appear once, so you cant reduce a champion's armor below 25% with this item no matter how many you or your team has.
this was made specificly for the AD casters now as was mentioned by the development team.
many of them are able to apply the full stacks within 1 combo and are able to apply it again,
most bruisers actually dont even do physical damage on their abilities, they're mostly magical damage. the ones Im talking about are like sion or volibear.
This item is best used on AD carries that do nothing but physical damage.
heres a good checklist of what you should think about to determine if you should buy it
1. does your champion have AD ratios?
2. are your champion's abilities physical damage?
3. do you cast your abilities as soon as they come off cooldown often?
4. do your abilities do multiple points of damage?
if you answered yes to the first 3, then this is a good item for you, if you also answered yes to the final point, then you probably should make this a core item