where to get a Ulzuin's Pyroclasm blueprint?

I wanna craft a Ulzuin’s Pyroclasm, anyone can tell me where to get a Ulzuin’s Pyroclasm blueprint? Can I buy it from merchant or have to farm in some specfic place?

You need to farm for it, but you can also check out the trade section. Someone might have a spare.

You can also give the materials +/bonus stuff to someone who has it to craft it for you

I can craft if for you if you want. Just PM me with a link to your steam profile.

Blue (i.e. Boss) Enemies, Nemeses, and Troves.

Those are the only places I have ever seen plans drop.