Before he left, his scream of betrayal was heard by the triumphant humans. “Dule! Base traitor! I sense your art in this artifact assembled by the last Yalain. Thee and thine are banished from Our sight for all time, and ye shall be hunted until the stars fall from their course! Marked are thee!”
You hear a childish voice say, "Long ago there were five, but now there are three. They will have their revenge."
The Fourth Sending of Darkness
Ilservian's surviving friends became corporeal once more and raised the Thorns, using them to alter the patterns of magic in the world. But Isin Dule had misgivings. He remembered the final days of the last war, his friend's blank expression when the planar energy was felt, and the compulsion that had come upon him. “It is likely a trap, brother,” he told Ilservian, and still they had gone. 
Isin Dule's faction of shadows seemed alarmed by the Hopeslayer's blind rage, and appeared to be working to keep him imprisoned. Fearing that Ilservian Palacost is insane and will bring about the destruction of the world, one of his first acts is to command his forces to guard the Nexus Crystal from destruction. But this first attempt to protect the council's trap failed. The humans of Ispar gained access to the Nexus Facility, and a second piece of Ilservian's prison was destroyed. 
To that goal, Isin Dule raises a Shadow Spire on Caul. Some members of the Raven Hand have willingly embraced the Shadow and joined his cause.  Others, such as Archon Merille he does not trust.
Isin Dule finds a way to remove the "taint" from those following him by studying the work of Aerbax. Asheron sends him one of his Lifestones, and the Shadow faction of Isin Dule joins the Isparian people.