Wind Organ of Void空虚のウィンドオルガン

A ritual instrument that works with wind blowing through its cavities. The sound it plays is perfectly tuned to attract a beast of oblivion.
In-game description

What is Wind Organ of Void? Features and uses

Wind Organ of Void is a rare item in Core Keeper (Placeables & furniture). It is crafted from Oblivion Fragment ×10.

Wind Organ of Void key points (from the game data)

Sells to merchants for 106 Ancient Coins.

Calculated and summarized by this site from the game data (1.3.0.6).

Wind Organ of Void mechanics (checked against the game data)

The Wind Organ of Void lures the void titan, Oblidra.

Written by this site from values in the game files (1.3.0.6 prefabs and configuration files).

Wind Organ of Void notes

Placing it less than 300 tiles from Oblidra in Breaker's Reach while the boss travels underground draws Oblidra to it.
The organ is used up when Oblidra arrives.

These notes cover behavior that the game files do not show directly. They are based on facts from the Core Keeper Wiki (Fandom) page "Wind Organ of Void" (CC BY-SA 3.0), rewritten in this site's own words.

How to craft Wind Organ of Void (materials)

How to craft Oblivion Fragment : use it while carrying the materials below

Material	Amount	How to get the material
Oblivion Fragment	× 10	Enemy

Crafting time: 2 s