Emerald Claw, are they more tied to Dollurh or Mabar? Which would they revere more when it’s coterminous for the time to do some dark, apocalyptic ritual for the PCs to stop. How to Compare/Contrast each option to use as DM.? Mabar is thus the more likely option. However, I could see a weird "Dolurrh Jailbreak" scenario where they perform a ritual to release a lot of "undigested" ghosts from Dolurrh, seeing it as saving these spirits from dissolution.

— Keith Baker (@HellcowKeith) November 16, 2020

The purpose of the Blood of Vol (and thus the EC) is to AVOID Dolurrh, which they see as eradicating the soul. They harness the power of Mabar for their necromantic rituals. If you read Exploring Eberron, Lady Illmarrow has potential ties to Mabar's Queen of All Tears.

— Keith Baker (@HellcowKeith) November 16, 2020