Please update this to drop off a Shai'din Bloodomen who spawns in the Korucust bridge camp. I took a couple groups to kill the royals on Coirnav and we did not get the drop from an Imperial Advisor. After inquiring about buying loot rights in zone, I was told by someone who had the shield that they got Tatrinek's Curse off of a Shai'din Bloodomen who spawns in Korucust's camp. He said the drop rate was about 1 in 3 and that a good Koru group would net me the piece. Managed to run into a friendly 6 box who had seen the piece an hour before I got there and within another hour they had one rotting for me to loot. Hope this helps some people stuck because it is much easier to get to this mob than the advisor standing behind the queen.
15 kills, finally obtained this drop... sucked having to deal with 5 pathing mobs and working around fully-spawned King and Queen rooms within the 19-minute respawn timer. Good luck!