Shriek Cores?

[Tansorma]

Where in the world do I consistently get more of this item? I know the wiki says Hyen sells them but uhh... he doesn't, and I gave him all three Merchant Maps, unless there's a 4th one I don't know about. The shop in the Camp only sells 5, ever, and as far as I can tell, its a rare drop from Necros so farming them is kinda miserable.

I'd really like to get more of them, they are extremely helpful in the Penultimate Fight to stop them from cascading into their ultimate form, plus it makes normal blader fights so much easier.

Kinda obnoxious that a consumable that already extremely situational is also extremely hard to get your hands on.