Redmoon Hall

Redmoon Hall is the Dreadgod cult of the The Bleeding Phoenix, a Dreadgod who primarily relies on blood aura. The cultists merge with Blood Shadows in order to gain power. Their primary purpose is to go out into the world and obtain blood aura for the Bleeding Phoenix to feed upon.
In books 7 and 8 (Uncrowned and Wintersteel) Redmoon Hall competed in the Uncrowned King Tournament in Ninecloud City under the aegis of Monarch Reigan Shen, along with the other three cults.

Founder, Red Faith

The Sage of Red Faith or the Blood Sage, and his Blood Shadow, a Herald dubbed Blood Moon. Redmoon Hall was founded by Red Faith. He used to be a researcher.

Red Faith, The Blood Sage:
The Blood Sage, founder of the Bleeding Phoenix’s cult, looked as though he had no blood in him at all. His skin was as pure white as his hair, which was so long that it reached down to his bare feet. His black-and-red clothes were tight enough to reveal his skeletal frame, and lines of red paint ran down his cheeks from both eyes like tears. He perched on the windowsill, hunched like a monkey, chewing on his thumbnail and staring at her with unnerving intensity. She felt nothing but disgust for this creature. At some point in the past, he was supposed to have been an accomplished researcher, pioneering investigation into dreadbeasts and the nature of spirits.
—Wintersteel, ch 6

His Blood Shadow

Red Faith’s Blood Shadow is named Blood Moon. He’s at Herald rank.

Blood Shadows

The Bleeding Phoenix is the only Dreadgod that can be physically destroyed. However, the Bleeding Phoenix molts thousands of its feathers as Blood Shadows that scatter far and wide. Each Blood Shadow carries a fragment of the Dreadgod's consciousness. When a Blood Shadow finds a powerful sacred artist, it latches on to their core as a parasite and begins feeding from the host's madra, blood, and life force. The Blood Shadow returns to the Bleeding Phoenix when it is full to deliver the stolen power. In this way, the Bleeding Phoenix gets stronger even as it rests. This is the basis of power used by Dreadgod cult followers in Redmoon Hall.
As far as we know, the only sacred artist to resist a Blood Shadow — which is to say, the will of a Dreadgod — is Yerin, when she was only a child of seven.(see Skysworn) For a almost ten years, she wore that Blood Shadow as a belt.
“Redmoon Hall. Other than wearing red and black, they had very little in common —- some were followed openly by their Blood Shadows, but others did not keep theirs visible.” (Uncrowned, ch 9).

Redmoon Hall is made up of many cultists, but the most significant are those who merge with Blood Shadows, small representations of the Phoenix's power. These are further divided into vassals and emissaries. Vassals are mindless, controlled by their Blood Shadow. Emissaries are the other way round. They are helped by their Blood Shadow, but retain their minds and powers, which makes them formidable threats. The Sage (Red Faith) feeds his Blood Shadow to control it. Dubbed Blood Moon, his clone is at Herald rank, and is not truly loyal to the Sage.

Known Emissaries

Underlord

Longhook † — Attacked citizens in Blackflame Empire. Killed by Eithan Arelius in book 5, Ghostwater

Yan Shoumei — (Truegold in Ghostwater). Advanced to Underlord to compete in Uncrowned Tournament with her Blood Shadow, Crusher. Eithan threw his match to her in exchange for his terms with Reigan Shen, in Wintersteel, book 8. “Her hair hung over her eyes like a hood, and her Blood Shadow slithered formlessly around her.” (Uncrowned, ch 9)

Blacksword — competed in Uncrowned

Overlord

There is one confirmed Redmoon Overlord, but the name is unknown.

Bloodspawn

Can be manipulated by Blood Shadows. Within the Phoenix's miles-wide range of blood aura, natural spirits known as bloodspawn are formed. Vaguely humanoid in appearance, they rise from sources of blood, including open cuts on still-living people. (Skysworn, Chapter 9; Bloodline, Chapter 15) They aim to wound those around them, increasing their own numbers and providing more blood madra for Phoenix, their master.