Water or Blood
The Delusionist Heresy
They believe that there is a greater power than the gods and call this power the Deluge. They deny the need to worship gods and are currently much persecuted, though there is some hidden traction in the common folk that worries the church.
In addition to their underground traction, there are many open members who now show astounding gifts related to manipulation of water magic they claim comes from tapping into the Deluge.