Go to Sebilis. Find a Sathirian Blood Vase ( -75, -125, 520 ) /waypoint -75, -125, 520 in Venril Sathir's Hall. This is on the same level as the Reet Slave Mines from the quest before, on the left side of the corridor leading to Venril Sathir's lair, a raid zone.
Fighting your way there will be tough. Mobs are 84^^^ to 85^^^, and they can cast a noxious ST fear spell.
Gather the Blood Vase.
Cast the Transmogrification spell (Only works within Sebilis).
Place the vase at the original location for the Phylactery, ( 181, -8, 369 ) /waypoint 181, -8, 369 just outside the Audience Chamber.