I have retrieved the Ashes of Anephas and talked to Kerah, but still can't get Anephas to appear. I have heard that you need an oblisk for the divine light pedestal, but I can't find it. Please help!

When you talked to Kerah in her funny little shrine did you notice an odd looking object on the opposite side? That is the portal of Isis, activate it and you will get the obelisk of light. Put it on the table which has the light beam shining on it, then carry the big gold'n'silver obelisks into position on the odd looking floor tiles until the beam is reflected all the way down to the altar. Put the ashes on the altar and hey presto, Anephas appears and you can party!