I just wanted to mention this on the forum in case anyone needed it. I just happened to get the +15 shadow to cloak enchant while randomly killing things in Netherstorm... it's got a 0.4% drop rate per WoWHead, and it's BoP. I now have the skill and the adamantite rod to cast it, and figured I'd post this in case anyone wants it.
It's quite expensive; 8 primal shadows and 4 large prismatics. I don't expect to do many of them, but I figured I'd let everyone know it's available in-guild.
(I often have prismatics if you're short.)