From PathfinderWiki

Oversee the operations of the Red Mantis
Source: Inner Sea Faiths, pg(s). 6-8

The Vernai, also known as the High Killers, are the ruling council of the Red Mantis assassins, second in authority only to Blood Mistress Jakalyn herself. They live in the Odalis section of the Crimson Citadel on Mediogalti Island.12

Members of the Vernai are almost invariably female, although there is no absolute prohibition against male members. Although they address each other by name, they keep their identities a secret to any outside of their circle—to non-Vernai they are known only by their titles. Tradition has it that there are 13 members of the Vernai, but that number can vary.23 In the past, their numbers have dropped as low as seven and gone as high as 23.3 Estimates suggest that about a third of the Vernai are slayers.4

The Vernai are not merely assassins. The Red Mantis are a religious organisation, so the Vernai are also responsible for interpreting and acting upon the will of Achaekek, and the Blood Mistress is considered the authority of his will.23

Heretics of Achaekek who disregard the Red Mantis assassins' religious role are considered to be enemies of the faith by the Vernai.5