Azmeri Reliquary Key Acquisition?

Can some one please tell me something about the acquisition of this item. Is it random ? Do you HAVE to interact with wisps ? Cause the wiki is quite cryptic about it. It says "Azmeri Reliquary Key has restrictions on where or how it can drop." Every other key in the game is a bit more specific. I basically wanna know if its somehow farmable or if i can do something to make it more likely for it to drop... i cant ask the people who currently list it for almost 400 div at the currency exchance... so im asking here as my last straw