Speak with Hierophant Prime Jarrakas. ( 625, 253, 1337 ) Copy/waypoint 625, 253, 1337 (ensure this step is done and the quest reads 'Ensure Choosooth's mission success' before leaving for Kunzar Jungle)
Complete the instance, then find Chosooth, who is in the very back of the zone through a false-wall behind the last named ( 38, -5, -1215 ) Copy/waypoint 38, -5, -1215. Just follow one or other of the floating heads the boss' death spawns, and Walk through either of the illusory wall sections, like ( -16, -5, -1130 ) Copy/waypoint -16, -5, -1130, then down a hallway all the way to the back. Talk to Chosooth to receive the Vial of Iksar Blood. If you have completed the quest Hold on to the Phylactery you will not have to return to the Hierophant, you will find Chosooth automatically, reveal to him that you have the phylactery and not Venril, and he will give you the Vial of Iksar Blood automatically. (Not sure why that last was written - neither Chosooth or Dominus Rile are Hierophants, and the grammar ambiguously makes it seem that you can skip the last step to report to Dominus Rile, but it's the prior step with Chosoon that gives you the vial of blood. I just did both steps because the note made no sense.)
