I'm about 800 hours into the game now and I have not had any of the following "big money" legendaries drop for me.
The Witching Hour
Mempo of Twilight
Litany of the Undaunted
As a result, I'm stuck with toiling month after month to scrounge up 50 million to buy "sub-par" legendaries and sets for my character. (i.e. saving up 60+ million gold this month to afford a DEX+AR Inna's Temperance). I can solo MP7 with a couple of deaths, but my gear is very mediocre compared to the vast majority of the DH's here on this forum.
Is it because I only play DH and no other class? That I have never spent a dollar in RMAH? That because my gear is subpar that I will only find mediocre legendaries and sets?
I have found everything for Immortal King's, Tal Rasha's, Inna's, Zunimassa's, even our own Natalya's sets, Skorn, Echoing Fury, Stone of Jordan, Mara's, etc but never any of the above mentioned items.
I have found a dozen Vile Wards throughout the months, but zero of the list above. Why?
1 Witching Hour
2 Ice Climbers.
The only good one I've found, is the Witching Hour that my DH is wearing.
So don't worry about it. RNG is a troll.