Legend
This quest has no legend.
Location
Dangers
All monsters in Dreamer's Challenge Quest.
Reward
Nightmare Outfits and addons, achievement Nightmare Walker 
Outfit
To get anything of the outfit/addons, you need to have the highest rank "Lord Protector" of the Nightmare Knights, or get invited by a player with this rank.
Rules how the outfit/addons work:
First you need someone with highest rank on your server (so 3000 essences handed in). That one can then make 3 kinds of scrolls (and sell them).
If you use the 1st scroll, you get the outfit. To be able to use the first scroll you must be member of the Nightmare Knights (rank "Novice"), so you must have finished Dream Challange and chosen NKs. But you do not have to have handed in any essences.
If you use the 2nd scroll, you get the first addon (lance + shield). To be able to use the second scroll you must have the rank "Initiate " (500 essences handed in)
If you use the 3rd scroll, you get the second addon (helmet). To be able to use the third scroll you must have the rank "Dreamer" (1500 essences handed in)
Consequence: First you need someone with highest rank "Lord Protector" on your server, than it makes sense to collect essences for own addons (or collect straight to 3000...)