When you go to queue for Gamma dungeons, Gamma Forge of Souls/Pit/Halls are listed, but they aren’t actually a thing. There is only normal and heroic. It would seem a Blizzard employee missed a memo.
The dungeon finder might group you as though it was a thing–I haven’t tried–but there is ONLY heroic above normal. Manually zone into heroic, and there is no Titan disc.
Good news is that you receive Defiler’s Scourgestones from those heroic bosses–and only heroic. My alts that ran normal don’t have any.
On a related note, I saw some people say that Defiler’s dropped in regular heroic–they must have been referring to these three, and not any of the older ones. Since, you know…that’s the whole point of Gamma.
As far as the daily Gamma quest being completed on regular heroic, it may be the same situation.
They are gamma difficulty “according to Blizzard” so they drop the same currency rewards, and they you can also queue for any one of them specifically (dont do H HoR because the LK loot is bugged) and get both the heroic daily and gamma daily done.
I wondered about that. I didn’t have those insta-18 mirrors pulls at all. Did it on my main priest and had the same pleasant ride, plus as someone else noted, I had ~220k hp with my pvp gear on (highest ilevel).