Basically, the item upgrading system enhances the item performance. And the range of upgrading level is from +1 to +24 and as the +level goes up, the success rates become more challenging.

When the item reaches +17 or higher, 5 different types of special visual effect is randomly applied. (Fire, Ice, Water, Lightning, Dark)

First, you need to find the upgrading NPC in each starting village or headquarter.

The upgrading NPCs are as below.

DeFugel
[Upgrade NPC] "Luji" in Lonbarei Training Camp
[Upgrade NPC] "Titina" in Magnaksia Military District

Craxion
[Upgrade NPC] "Purel" in Kuznets Advanced Base
[Upgrade NPC] "Boyd" in Headquarter of Blo Brunak Magic Knight Guild

Double or right click the NPC and select "Trade". Drag the item you want to upgrade on "Register Gear" slot and put the scroll on the scroll slot. If you press "OK" a confirmation message window will popup. If you press "Yes", upgrading will be proceed at free of charge.

A Window will popup to introduce premium items. "Potion of fortune" increases the success rate to 200% and the "protection of Upgrading" prevents item disappearing when upgrade fails.

If you use "Potion of Fortune" and "Protection of Upgrading" small icons will be shown next to the health bar. You must double click the item in the inventory to activate and you have to get off the mount to do so.

If you fail to upgrade, the item can be disappeared. If you used "Protection of upgrading", the items will not disappear but it may down grade from 0 to -2. Using purification scroll to down grade will never fail and your item will not break in the process.