Tyriyn Bythronian of Ubl is the High Priestess of the Temple of Lorminstra in Wehnimer's Landing. She is the very old black robed woman who performs the ritual for offering sacrifices in exchange for deeds. She refers to herself as a "Daughter of the Night, High Priestess and faithful servant to the Lords of the Great Moon." This language suggests she was originally the local Eldest priestess of the Sisters of Eissa, who have a temple in most cities and are typically the ones who can perform resurrection magic. They usually wear white robes with belts indicating rank, but wear black hooded cloaks when traveling. The hooded figures at the tapestry, however, are described as being men. The Lord High Cleric may be the old priest who explains the deed ritual the first time it is attempted by an adventurer.
The Sisters of Eissa (Lorminstra) are a religious order in Shadow World who abhor killing except in self-defense, even things such as orcs and goblins, because they believe all animals have souls and life is sacred. They are healers who only ask for donations proportional to what has been exchanged. Their symbol is the golden key, symbolizing the six keys of Eissa, which are: Life, Death, Mind, Body, Soul, and Void. In the later lore they believe souls who have not earned the afterlife yet will return to the world in some form of reincarnation. They do not have congregations and coexist with other faiths.
The premise of the deed ritual is that sacrifices are "gifts" being given to the High Priestess as a high tithe for her intercession, but that she has substantial influence with the death goddess, who the acolytes like Bandur Etrevion refer to as Death. It is explained that the goddess has no use for "the trinkets and baubles of this world", but she acknowledges we value them, so we must "offer proof that your life is worth more to you than the treasures you possess." The High Priestess prays on your behalf, but warns "the proof must be overwhelming" to the mind of Death. They are recorded in a Book of Passing.
The goddess herself decides whether this sacrifice is convincing by either making the room cold or the incense burners bursting in brilliant blue flames. There is a dark parallel to this in the tapestries and incense burners in the Sheruvian summoning chamber, where this ritual is also symbolically represented in the Dark Shrine of the Broken Lands and the purgatory throne room of The Graveyard. It might also be argued that the High Taskmaster who directs sacrificed spoils, which are offered on an altar, is the Council of Light analog to the High Priestess with Grand Poohbah analogous to the Lord High Cleric.
The ritual itself is considered a puzzle, though the steps are explained. The following are messaging variants upon entering the tapestry:
As you approach the black velvet tapestry, the hooded figure stands and steps in front of you. In a quiet but firm voice the hooded figure says, "I cannot recall thy face, XXXXX. Either this is thy first visit or thy features have become twisted to my eyes by the touch of Death's hand. But it matters not. This is the Temple of Lorminstra and you are welcome. Acolytes are waiting to assist you on the other side of this curtain. May you find the answers that you seek." As you approach the black velvet tapestry, the hooded figure stands and steps in front of you. In a quiet but firm voice the hooded figure says, "To the Gods, the life of this world is no more than the flicker of a candle. You may enter, XXXXX." As you approach the black velvet tapestry, the hooded figure stands and steps in front of you. In a quiet but firm voice the hooded figure says, "The quest for life eternal is common in these lands, XXXXX. May our Gods find favor with thee." As you approach the black velvet tapestry, the hooded figure stands and steps in front of you. In a quiet but firm voice the hooded figure says, "One must admire your lust for life, dear sir. Enter XXXXX, and may Lorminstra shine favor on you." As you approach the black velvet tapestry, the hooded figure stands and steps in front of you. In a quiet but firm voice the hooded figure says, "May Lorminstra grant you even more deeds, XXXXX." As you approach the black velvet tapestry, the hooded figure stands and steps in front of you. In a quiet but firm voice the hooded figure says, "I see that death has yet to make a final claim to thy soul, XXXXX. Welcome back."
Behind the Scenes
Tyriyn Bythronian seems to be part of a very old tradition of making easter eggs out of medieval Welsh. The words "tyriyn byth roni an" are possibly meant to translate into "never want to ring the", where the ritual for making sacrifices to Death involves ringing the chime with a mallet. Her first name would be pronounced like Tyrion from Game of Thrones, which was based on the Welsh "tirion" for "kind or gentle." In this spelling Tirion is a girl name, and also can be taken to mean "compassionate." Byth can mean "never" or "always", so her name might also be intended to mean "the ever compassionate one", or the emphasis with "byth" could be on foreverness to the effect of "compassionate eternity." Ubl seems to be a medieval German nickname, based on ubel meaning "bad" or "evil" or related to possessions.
While there were a number of location terms from Shadow World which were changed without being made part of a conversion glossary, these are usually obvious quasi-anagrams that can be identified by inspection. These were generally retconned to be part of the Turamzzyrian Empire history. "Ubl" does not seem to have a clear counterpart term, possibly having been another short word such as Lys. With her name being a real world reference, it might have always been Ubl, though the meaning is unclear. The Lord High Cleric of the Temple is referred to as a "him", but either could be Poohbah's "adversary." The High Priestess does not seem to give any messaging variation for the Council of Light. The Hall of Sacrifice dais with the old priest is blocked by divine intervention from even the Assistant Masters. Poohbah brags that that they are "beyond the reach" of his adversary. In historical context this should be Lorgalis, the warlord of "Ulor", who also subversively infiltrates centers of power by posing as a wise old man.