The Mesmer Collective is a semi-secretive organization of mesmers, as the name implies. Most of its members are unknown, though Countess Anise and Kasmeer Meade are known members. Certain extremely powerful mesmer spells are known only to the most elder members of the mesmer community, and are kept a secret from outsiders.
The Collective also sends members to investigate certain unknown occurrences where mesmer magic is or may be involved. For example, when the veil surrounding Viathan Lake (later discovered to be concealing the Tower of Nightmares) was identified to be a mesmer illusion, the collective sent Kasmeer to investigate.
In order to become a member of the organization, a mesmer has to be sponsored and invited to join the Collective.