Based on one page in the wikipedia, it seems like I need to learn both that I am Muudari and that a human blood is nothing special of a sacrifice. I did not notice an option to join in my first play through with the knight at dragon coast. I had saved over the save file before this encounter so I cannot test it without starting from scratch (and I would rather wait until the new update to do so). Do you only need to pass the intelligence check after the shards of fate quest or do I need to side with the Undermother as well? I would rather kill the Undermother for her hide.... (It took several tries, but I did manage to kill both the Prophet and the Undermother.) Also, what happens when you let the Prophet deal all the damage to the Undermother and die while doing so? Do you get the drops from the Prophet? If so, that option would have made the fight so much easier....