Mystra
The Seven Stars, goddess of Magic. One of the twelve gods of Verein Kirche von Arkhelle. Her current name of Mystra was used by some tribes of humans back in the Age of Enlightenment when her worshippers and students in the Acropolis of Kereskaa called her Kereskaa.
Her symbol is that of seven stars, referencing the schools of magic, and the phrase is referenced often in writings about her. On the wall of Irann Rhogar's house, the words ‘Petty tyrants of lesser gods will not stop us. Seven stars will burn bright this night.’ were written in the blood of two Raven Guards. In the amphitheatre of the Acropolis of Kereskaa, the phrases ‘Seven stars light the night sky’, ‘Seven eyes perceive what hides’, and the partial phrases beginning ‘Seven hearts yearn for—’ and ‘Seven stars and seven—’ are carved in the walls in a language Mira doesn't recognize.
According to Suithrathus Luirmo, Master of Divination, Kereskaa and her most devoted students built the Acropolis to hide and secure the Dragon Orb of Drimysthonantas, said to be able to control black dragons supposedly because it contains the soul of a Great Wyrm from the Age of Great Ruin.
Knives of Mystra
As arcane magic is forbidden in Kaarst, where the other gods of Verein Kirche have stained glass windows in Kade Sirrine Kathedrale, Mystra's window is blank, although there are a very few offerings on the altar beneath it. According to Uthan, anyone who openly worships Mystra is followed and searched by members of the church or Kaarst City Watch, and so those who do worship her do so in secret, calling themselves the Knives of Mystra. When asking about the history of this law, Father Glissan tells Vichthart the following.
‘Yes, Kaarst has some unpleasant history with the arcane, dates back to the Age of Decadence. When it joined the Empire, the churches were united, some exceptions were made to allow the city to maintain its laws banning arcane practice. The worship of Mystra is not outlawed, the arcane practices are.
The Tide doesn't seem to think the Knives take part in anything dangerous, although some members led by the Ashmaker do attack Kham and Vichthart in the street at night, according to Reiner Hoss, to make a public demonstration. During this attack, the Ashmaker cried out ‘Let it be known, the Faithful of Mystra will no longer be denied in this city,’ with witnesses clearly hearing the mention of Mystra and talking about it afterwards. On the pretense of helping to liberate the worshippers of Mystra, Etorn Hadaran and Irann Rhogar convinced members of the Knives to plant masses of explosive ashfire oil in a certain position underneath Kaarst, to be detonated at sunset on 15th Thelliea, the same night that Rhogar was due to take part in a meeting of Kaarst City Council.