Why an item works on one carry and not another
Damage has parts that multiply: how hard, how often, and what multiplies it. An item feeds one part, and some carries never use it.
Checked for patch 18.4. The numbers come from the live Set 18 data and follow every patch.
The idea
A carry's damage has three parts, and they multiply each other. How hard each hit lands: attack damage for attacks, ability power for abilities. How often it lands: attack speed, and for casters the mana that brings the next cast. And what multiplies the result: critical strikes and damage amp.
Because the parts multiply, an item that adds to the part your carry has least of raises its damage the most. Stack one part and every extra copy adds a smaller share to the whole. That is why carry builds mix their items: something for the hit, something for the speed, something that multiplies both. A carry only deals damage while it is alive and acting, so the item that keeps it there sometimes adds the most.
The parts are not the same for every carry. A carry that wins with attacks gets little from ability power. A carry that wins with its ability gets little from attack damage, but attack speed still helps most of them, because attacks build the mana for the next cast. Items with both kinds of stats fit either kind of carry, which is why they show up on so many boards.
The ranked games show the split. Each item below is counted on the carries of top four boards, by the damage those carries deal. The game review calls an item wrong for a carry only when carries of that kind hold under 15% of its copies and the champion's popular builds skip it too.
See it live
The items top four carries hold most in this set's ranked games, with their damage stats, sorted by the share carries of your damage type hold. Switch the damage type.
The items top four carries hold most, by the share attack damage carries hold
55%Attack Damage
10%Damage Amp
What it does
Perfect peace and calm for the holder - and all who face it.35%Attack Damage
35%Crit Chance
What it does
Gain Precision. Precision: Abilities can critically strike10%Ability Power
10%Attack Speed
What it does
Gain 7% stacking Attack Speed every second.45%Attack Speed
3%Damage Amp
What it does
Attacks and Abilities 1% Burn and 33% Wound enemies for 5 seconds. Burn: Deals a percent of the target's max Health as true damage every second Wound: Reduces healing received10%Attack Speed
20%Crit Chance
10%Damage Amp
What it does
Critical Strikes grant 5% Damage Amp for 5 seconds, stacking up to 4 times.15%Attack Damage
15%Ability Power
1Mana Regen
What it does
Attacks grant 5 bonus Mana.10%Ability Power
40Mana
What it does
Gain Mana after casting. When the holder gets a takedown, they deal % more damage for 3 seconds. [Unique - only 1 per champion]20%Attack Damage
20%Ability Power
1Mana Regen
What it does
Heal the lowest percent Health ally for 20% of damage dealt.Ally Healing: ?35%Ability Power
35%Crit Chance
What it does
Gain Precision. Precision: Abilities can critically strike30%Ability Power
1Mana Regen
What it does
Combat start: Gain 20% Ability Power every 5 seconds in combat.35%Ability Power
15%Attack Speed
1Mana Regen
What it does
Damage from attacks and Abilities 30% Shred the target for 5 seconds. This effect does not stack. Shred: Reduce Magic Resist55%Ability Power
15%Damage Amp
What it does
This humble hat can help you make, or unmake, the world itself.
From this set's ranked games in HexKey, the ones the game review is calibrated on: copies on carries with two or more damage items, on top four boards. Each tag is the class the review gives the item from its stats.
The rule of thumb
Feed the part of your carry's damage it has least of, with items carries like it actually hold.
Check yourself
Your carry deals attack damage. Which of these items do attack damage carries almost never hold?
Pick an answer.