I am curious as to whether set blacksmith plans sometimes drop only from certain sources. I am under the impression (right now) that all blacksmith plans drop unniversaly and random. Unlike the legendary crafting materials where you have to fight specific super-bosses.
Is this the case?
Can I get all pieces of the "Hallowed" set (http://www.diablofans.com/forums/diablo-iii-misc-forums/theorycrafting-and-analysis/82607-plan-hallowed-defenders-need-advice) Randomly throughout the rift, without having to farm a specific situation?