How To Corrupt Gear
1. Using a Vaal Orb:

The most common way to corrupt an item is by using a Vaal Orb. This currency item applies corruption to your gear, resulting in unpredictable changes. After using a Vaal Orb, the item becomes permanently corrupted and cannot be modified further. Here’s what you need to know:

Effect: The Vaal Orb may add new mods, change existing ones, or have no effect at all. It can also potentially destroy the item or change all its sockets to white.
Risk: Because corruption is random, you may end up with either a significant upgrade or a detrimental change to your item.
2. Using an Altar of Corruption:

You can also corrupt items using an Altar of Corruption. This method does not require a Vaal Orb but involves finding an Altar of Corruption. Here’s how it works:

Location: Altars of Corruption can be found in the Temple of Atzoatl in the Incursion League or in the Vaal Ruins in Act Two. The Temple of Atzoatl contains the Locus of Corruption, which is a dedicated area for this purpose.
Effect: Similar to Vaal Orbs, Altars of Corruption will corrupt your item with one or two random modifiers. There is a risk of destruction or significant alteration.

The link (https://www.mmoexp.com/Path-of-exile/Currency.html) leads to additional details about the game.