The Cult of Azeroth
Do not look at them, do not run away, do not acknowledge them. For if you do, you'll be trapped for eternity in an unending, decaying madness.
The inner working of the Azerites is mostly unknown. There appears to be a central figure, usually female, which they call "Vauta" which means mother. There are members with specific roles, most easily identified is the herbalist, who carries a large basket of various herbs and materials.
Azeroth is the god that they serve, little is known about him, however, it has been extrapolated from the cult's behaviour that he goes about on whims and wishes to spread his madness.
Mythology & Lore
Azeroth is a first-born god, before the time of thinking creatures. He is known as the god of madness, although this isn't entirely the case. Azeroth drains the minds of those who become indoctrinated into the cult. These minds are not consumed in the normal sense of destruction and then transformation, the minds are added into Azeroth's, driving him even madder. He does not spread madness, he creates and consumes it.
In the time before monsters, the land was barren with only mountains and vast sands covering the world. Azeroth is a first-born god, there are two generations of gods. The first-borns are unknown to the current sentient races, they are only known by Vindnir, the eldest second-born god. Azeroth is the only first-born in recent times to bother with the new world, his cult is an extension of his mind as he goes about on various whims.
The Azerites worship their god by carrying out his will, Azeroth gives nothing and only takes. He slowly consumes their minds, adding them to his own, this causes their bodies to slowly decay as well. The only directive they have followed for centuries is to gather more members to feed his hunger. To do this, the members must cut the victim with the ceremonial blade, this blade contains a fast-acting poison. The incense burned has special properties, it slows the poison to prevent the death of the victim, once this happens Azeroth can start to consume their minds. The music played seems to be important, however, it's exact purpose is unknown.
Political Influence & Intrigue
They travel the surface of the Korvvind in slow, meandering paths. Any place they choose to travel through becomes theirs for the time they are there, for everyone knows that the Cult of Azeroth must not be challenged, lest they wish to be spirited away.