The Calm Before the Storm

A member of the esoteric Heralds of Aevilok, a doomsday cult dedicated to preparing the world for its inevitable end, utilizes the Mithral Spire's connection to the other Planes of Existence to open a portal to the Plane of Air and summons the Elder Tempest.

The adventuring party who thwarted Shepherd in Horizon was fortunately there on the behest of King Dorian Havik and was able to stop the Herald before his ritual could be fully complete.