EU+US How to obtain daggerspine attack plans on a 19

[Laurenti]

I think im missing some quest or prereq for this item drop, but I have no idea what it is. Anyone happen to know if there is anything that precludes the plans dropping? I've done most of the zone, but still have some random quests in tarren mill to do. Any help would be great. Thanks, neap xd xd

 

[Holythane]

I did full zone and would not drop killed a lot