Ghastly Wail Mod Wiki & Guide

You need to damage a ghast until it has low health, then position it so it dies while inside an activated Nether portal frame. The easiest methods are using a bow, magic damage, or luring it into portal fire. Timing is key—the ghast must be within the portal blocks when it takes the killing blow.

Yes, the portal must be fully activated (lit with fire) for the ghast death mechanic to trigger. An unlit portal frame will not shatter or produce crying obsidian when a ghast dies inside it.

The entire portal structure shatters and breaks apart, and all the obsidian blocks are converted into crying obsidian and dropped as items. You can then collect these crying obsidian blocks from the ground.

You can farm it repeatedly by rebuilding the portal and luring new ghasts to die in it. This makes it a viable alternative to bartering with piglins or searching loot chests, though it requires effort to set up and maintain.