Open the door to the chapel in Nek 3, carefully staying as close to the door as possible without entering. You will be attacked by at least 1 of 4 pools of gore. These can be non-aggro if you don’t stand too close to them. Have the tank pull each pool of gore to the doorway and fight it there. As each one dies, it will coalesce with an exsanguinated golem (non-aggro) lying at the base of the altar. As the final pool of gore joins this bloodless golem, it will arise and become the aggro plasma golem, but will not attack immediately if the party stays away from the alter, very close to the doorway.