Upgrade Items

**Upgrade items** are accessories used to improve stats of player units. They come in a large variety, and can affect various characteristics in different ways.

Items are used by putting them in their respective slots on a unit's page. They can always be unequipped or swapped for another one. By pressing a box icon on the main screen, players can access a window that shows all items they have, sorted by rarity and level. Tapping an item will show an overview of its stats. If an item has a lock icon, it means it is being used by a certain unit. That unit's portrait will be shown on the item's overview screen. A single item can't be equipped by multiple units.

Support items such as Empty Barrel, Medkit, and Turret can't use accessories, as they usually rely on characteristics different from those of human units.

Items can be found inside tappable vehicles in missions (can only be collected once), and by opening lockers rewarded at the end of supply runs. *For more information, see:* Supply Runs.

Items can also be received when breaking the barricade in the Corn Farm Event and when participating in Skirmish to combat other players. The latter has a small chance of happening, and only provides common-tier items. For detailed information on item drops in Corn Farm, see its page.

## Stats

There exist four category of items, each providing a guaranteed increase to one of the units' core characteristics:

 Knives
 Watches
 Books

Each item in the game is randomly generated, with there existing an incredibly large number of possible stat bonus combinations. Once an item is found, first it gets a random main stat assigned. Then, the game determines how many bonuses it should have. It can have either a maximum amount, or maximum minus one. Once that's done, it assigns the item 3-4 (this value is different for percentage based items) random extra stats (substats) that do not repeat. Each stat has a range of default values.

The game follows a specific order with application of bonuses. First, it applies percentage multipliers on base damage. After that, it adds up flat bonuses. For example, lets imagine a unit with 30 base damage, who has +20% multiplier and +10 flat bonus from items. First, the game uses multipliers: 30 \* 1.20 = 36. And then it adds flats: 36 + 10 = 46. 46 is the unit's resulting damage.

## Upgrading

Items can be improved by selecting them and pressing the "upgrade" button. This will change the layout of item window, allowing players to choose six items to "recycle". Recycled items add a certain amount of points to a level gauge. Once it's full, the item will receive an upgrade after paying the upgrade cost. Up to six items can be used at once. Each item costs a certain number of coins to recycle, which increases with its rarity. The amount of points obtained for each recycled item scales with both rarity and the item's own level.

Leveling items up improves their "guaranteed" bonuses. At levels 1 to 5, each upgrade increases the main stat by +3. If possible, level 6 upgrades and beyond increases it by +4. With each 3rd upgrade, a random extra substat is boosted alongside. The increase value of extras depends on which stat it is (generally speaking the value fluctuates at around a value of 1 to 3. For example one time might upgrade from level 1 to level 2 and the stat will go from 7+ to either 12+/13+/14+). If the item does not have the maximum number of substats, it may obtain a new one instead. Tiers determine how many levels and extra bonuses an item can have.

 Rare
 Epic
 Legendary

The above recycle point values are provided for level 1 items. If recycling items of higher level, they provide a greater amount of points, while their cost stays the same.

*For detailed information on extra stats, their upgrade values, recycle values, and item levels, see*: Item Data.

## Item Sets

Each upgrade item in the game exists as a part of a set.

A special bonus is activated once three items from the same set are equipped on a unit. Understanding this, this leaves the fourth item open for any set to be equipped without affecting the others. Equipping all four items from the same set doesn't provides any extra benefits, but does allow a bit more flexibility in using items from other sets so one can keep the set bonus.

Stat bonuses from sets are always applied the last, right after percentages and flats from items.

Some descriptions of bonuses are misleading, or provide a poor explanation of how the set actually affects its wearer. Please make sure to consult the dedicated pages of each set to get proper understanding of how each of them works. The below table only lists set descriptions provided in-game by developers.

## Trivia

* The revamped item system bears a striking resemblance to Genshin Impact's Artifacts system, encompassing various aspects such as the rarity of items, the upgrading mechanics, the utilization of item sets, and stats.
* The Big Boy item set bonus functions exactly the same as Chopper's special ability from update 3.6.3. His special was reworked for the second time to prevent Chopper having the same buff twice.
* There used to be a bug where Builder Abby was able to indefinitely fire her minigun when the Gambling set bonus was activated, assuming she has her level 13 Special Ability. As crit bullets do not consume ammo and Abby does not have a reload, she is left to fire away until she is killed. This was later fixed in update 3.8.2.