OVERVIEW:

The Crossing refers to a historical event in which various magical beings from many realms entered Midgard through the Northern Rift, an opening between worlds. It is understood that the Fae opened the Northern Rift utilizing Luna's Horn, and they were the first to enter Midgard.

According to Ruhn Danaan, Prince Pelias, the first Starborn Prince, led the Fae into Midgard. Pelias also eventually sealed the Northern Rift: "During the final battle of the First Wars, Prince Pelias and the Prince of the Pit (Apollion) faced each other... until the Star Eater struck the final blow. But not before Pelias was able to summon all the Horn's Strength, and banished the Prince of the Pit, his brethren, and their armies back to Hel. He sealed the Northern Rift forever—so only small cracks in it or summonings with salt can bring them over now" (234).