While these slots have a specific name, they are commonly referred to by the shape instead. There are 6 modification slots on each character.
MIN HERO YOU LEVEL MAX MOD
Mod Tiers are indicated by a letter A-E in the Mod Name and by color in the mod image. The max rolls any individual stat can have is 4 so any secondary stat with a 5 next to it will no longer be eligible to get additional increases.
MIN HERO YOU LEVEL MAX MODS
Mod Tiers determine how powerful the Secondary Stats on mods can be by allowing them to have additional increases (rolls) to randomly chosen secondary stats. It is important to remember that rarity is not taken into consideration for set bonuses so all mods do not have to be the same rarity to get the set bonus.
![min hero you level max min hero you level max](https://i.ytimg.com/vi/Y2Q7G4gHg9Q/maxresdefault.jpg)
The bottom number is the max increase characters will get when all of the required number of mods for that set have been maxed out at Level 15. The first number under Set Bonus is the minimum increase characters will get to that stat for having all required pieces, but some or all are not max level. The Mod Set determines the stat bonus characters get when they meet the required number of equipped pieces. For example the mod above could be referred to as a 5A mod. Rarity is mainly referred to as dots or with the actual number and the letter of the Tier. The rarity of the mod determines how powerful the Primary Stats will be and is indicated in the name by a Roman Numeral and graphically by dots just above the mod image. The name of the mod contains the rarity, tier, set, and slot. Each character is able to equip up to 6 mods at one time.
![min hero you level max min hero you level max](https://i.ytimg.com/vi/Sl7eam6O0VQ/hqdefault.jpg)
The system unlocks at Player Level 50 and characters must be Level 50 in order to equip them. They are the only part of the system that allows players to choose what stats they would like to increase.
![min hero you level max min hero you level max](http://4.bp.blogspot.com/-5ASxqIv29-Q/Ugi8yD5C0ZI/AAAAAAAABdE/ktEV5z8tt4I/s1600/maxresdefault.jpg)
Mods (short for modifications) are equippable resources that are part of the character progression system to increase the power of characters.