Trading with Path of Exile 2 Currency Other Players
The trade market is often the most realistic way to obtain a Mirror- if you have the resources. Here's how:

Sell high-end gear, Path of Exile 2 Currency, and crafting bases
Stack Divine Orbs (the primary trading currency)
Watch community trade boards or third-party tools (like trade macros and PoE trade websites)

One important caveat: the Mirror needs to be listed for sale, and prices can fluctuate wildly depending on the season and economy. Expect to pay hundreds of Divine Orbs, if not more.
How to Use the Mirror of Kalandra in PoE 2
Using the Mirror is simple:

Right-click the Mirror of Kalandra in your inventory.

Left-click the item you want to copy

This will instantly create a mirrored duplicate of the original item in your stash. The mirrored version is bound- you can't change it, but you can equip or trade it (unless league restrictions apply).

When Is It Worth Using?
This is where things get tricky. Since Mirrors are so rare, you don't want to poe 2 trade site use one on anything less than god-tier.