World of Warcraft Item Upgrades
Upgrades to items are a method to boost the stats of an item. Based on the type of upgrade it could boost an item's Mark Level or Rarity, and also boost other stats.

The process of upgrading gear in The War Within requires a certain number of Flightstones and Crests and each item has an upgrade track. Each upgrade increases the cost of the following one by a specific amount.
Item Level
The value of an item's base stats increase when it is upgraded. The value is the sum of all its leveled up benefits (attack magic attack, attack defense). Upgrades can be costly, dependent on who you employ and what you decide to do. This is due to the number of perks that need to be altered to upgrade an item.
It is also used as a gating requirement when waiting for dungeons, raids and scenarios. It can also be used as a gating requirement while queueing for dungeons, raids and scenarios, and to limit the amount of PvP gear that a player can wear (since PvP is capped at a lower level). Players can view their average level of items on their character sheet.
The level of an item can help players evaluate the power of equipment when they decide to buy or sell. It's a useful indicator of an item's quality and the amount of damage it's capable of causing. Comparing items in the inventory of a seller is possible using the item's level.
The item level can be seen by pressing the ALT key on your PC or using the left stick (L3) on XB1 and PS4. This will show the item's full description, including ilvl. You can also locate it by hovering over an item and typing /itemlevel in chat.
There are various theories on how the calculation of an item's level is carried out. One theory is that the level is a numerical value derived from a formula that determines the amount an item's stats are worth. It takes into consideration the fact that various perks have different value and that gems in sockets add to the item's overall value. This can result in a calculated amount for the item's ilvl which is typically close to Blizzard's real item level.
This is not the only thing that affects the value of an item. The degree of the area in which the item was dropped can alter its stats. For example it can increase the item's haste or crit score. Items dropped in higher-level instances will have higher ilvl.
Item Stats
The stats of an item are a major part of what makes or breaks an item for players. The game utilizes them in many ways to encourage players to not restrict themselves to a particular weapon, and to encourage players to experiment with other weapons. The stats of a base weapon are enhanced by the weapon's stat modification which are then enhanced by the player's level.
Item upgrades add to that by increasing certain stats of the item. The rarity of an item determines the cost of upgrading. An item that is white or grey for instance, can only be upgraded once however, items with rare tiers may be upgraded multiple times with higher prices.
Another way to change the stats of an item is by affixing it. These are special stat boosts that can be added to an item by the player, and come in a variety of sizes and shapes. The affixes can be used to provide items with extra damage or other special capabilities (such as reviving dead or reducing cooling downs), or to make them unique by putting a name on them.
Presently, all affixes are able to be changed by selecting them from the upgrade window and pressing the green button with circles arrows. This process will cost the player a specific amount of gold as well as items which can be added to the upgrade gauge in the same way as the other rerolling options.
In addition to Rerolling affixes and rerolls, players can also choose which stats they want to keep on an item when it is upgraded. The possible stat ranges for an item are determined by the level of the item, but every item is guaranteed to have at least 1 stat within that range, unless it is an exclusive item or an item that is a God roll from a boss of a raid.
Another thing that could change is the possibility to upgrade equipment without having to roll the affixes, or choose which stats to increase. Like the base equipment, this must be done per item and the interface for item comparison would not display all the possible stats at once.
Item Luck
The Luck stat of a player can increase the chance of finding items and the properties that are spawned by loot and the intensity of these properties. However, it doesn't directly impact damage or the ability to upgrade item s. It gives players an opportunity to get better equipment earlier in the game. This is more advantageous in early game runs since players tend to prioritize the scaling of weapons and defenses over raw damage gains.
Luck can also increase the chances of upgrading items at the Blacksmith. This is not to confuse with the Blacksmith's overall upgrade chances that increase with each level of the item. These can also be increased by using anti-materials, such as the Scroll of Strength and a Jewel of Blessing.
Weapons, armor, and shields can be made or spawn using the Luck property, which has an initial value of 40. These items can be enhanced by golden ingots, spined leather, or oak boards (depending on the material of the item) to give +40 Luck or to increase the luck of the item up to 140.
Certain items, such as the weapon with Hollow-infused components can also be crafted to increase the damage of any skill that is able to deal damage by 5percent. These items can be bought from the shop, or they can be constructed using the right ingredients.
Item Failure
Upgrades to items are a costly process and not all upgrades will be successful. Cash shop items can be used to boost the chance of success of an upgrade or to stop players from losing their item in the event that it does not work.
The rate of success of an upgrade is shown in the Honing UI. The percentage is the probability of successful upgrading an item. This can be increased with Additional Materials or Special materials. The probability of success can only be increased by so much, and the likelihood that an upgrade will fail can't be greater than 100%..
The success of an can be affected by the luck of the item. Every item has an average success rate of 25 percent, and each item that has Luck increases the chance of success by 5%.
The upgrade overlays for items are displayed above items in the inventory. This may block enchantment effects as well as other effects. If you wish to disable the upgrade overlays, the config option decoration.renderUpgradeOverlays can be set to False in the Item Upgrader CORE client config.