I got a huge sample of this pigment when it first came out (the MAC gals where I shop are pretty generous). This is a beautiful dark, smokey grey/brown but there is fallout and there are so many pressed shadows that are similar in colour but much easier to use so I didn’t buy the full size. It’s just a bit too messy for the end result.
Nebula is a deep, dark taupe with a little hint of brown around the edges, but it loses some of the brown you’d expect from taupe because of how dark it is–it’s still there, and when you apply it dry, it’s more noticeable. When applied damp, it has a more metallic finish and depth. Dry, it’s a bit like MAC Legendary Black. MAC Bloodline is lighter.