Diablo 4 Item Upgrades
Item upgrades allow players to raise the level of equippable items like weapons or armor, as well trinkets above a certain threshold. You can upgrade items at any NPC that accepts the appropriate currency.
Upgrade components are integrated into equipment to offer attributes bonuses and other effects. These are mostly slot-restricted, but there are some universal upgrades.
Rerolling
In Diablo 4, a player can reroll a item upgrade. This is accomplished through the Level Up mechanic, which stops the game and shows a list of four randomly chosen upgrades. The player can select one of the upgrades to continue the battle. Rerolling is the same price as the normal Level Up. However, players must be careful when selecting an upgrade since they won't know what the new stats will be until the item is changed.
The rarity of an item and its the level of its upgrade items determine it. Each upgrade items level increases the power of the item by +3.