The only NMs I know of are the low tier hydra (Grauberg) and khimaira (Uleguerand). That's just going off wiki, but it's probably right. I got one of mine from Dominion, and the other 9 from the Altepa quest. The quest took me three days off and on, but I got really lucky with it, as I only ended up with about 5 of each of the other seals. Following previous patterns though, and the patterns of the other jobs seals, I'd say there's one more NM somewhere that drops them, my guess is the T2 gobby NM in Grauberg, but that's all it is, a guess.