I posted this on the PTR forums. not getting much attention though.
While testing XT-002 Deconstructor, I noticed that I could cast Devouring Plague on the boss (skull level), but I could not cast it on his adds because they were immune to disease.
Also, the Death Knight in the raid had no problem diseasing anything during the encounter. I checked the parse and all of my diseases, Devouring Plague, were Immune. All of the DK's diseases, Blood Plague and Frost Fever, were not Immune and did damage.
So my question is. why can DK's disease machines and shadow priests cant? And why can I disease the boss?
Clearly this change must have came when DK's were first introduced and if anything was immune to their disease, they would be crippled. This change should be mutual.
You already changed it so Machines can bleed and be poisoned, might as well stick disease in there too.