Short answer: Gods who were killed during a conspiracy. Their domains are unknown, even to their former followers.
Over five hundred years ago, the gods numbered 36 - eighteen Lesser Gods, and eighteen Greater Gods. Most of the details of the war are lost or hidden in scrolls, vanished to the world. Those who survived either are unwilling or unable to speak about it.
It is rumored that the whole war was started by Pantxike as a prank, and escalated into a full-scale apocalypse. Other rumors suggest that Chelan Godking and Mingan worked together to cheat at the cosmic game of oneupsmanship between the Gods. And still others suggest that Daimonas was responsible, using his powers and influence to escalate a feud into the near-extinction of reality. Others claim it was all of the above, or none. Nobody truly knows but the Gods, and they refuse to speak of it.
What is known is that it started as a feud between Coranthiir and the now-dead Caribia, and culminated with Chelan's Defender of the Faith and the Lord of Spring, Rhoslyn Vernal, destroying Caribia, Lisse, and Oraith with the aid of the brothers Mingan and Shin. This action reverberated through time and the final ripples will not be felt for thousands of years. The ranks of the Gods shifted, alliances were made, and new enmities formed, as well as the creation of two new races by Sanoci: angels and demons.
With the alliance of Sa'ada, Mingan, Caribia, and Shin, Coranthiir was soon under battle and called for his allies - his mate and daughter, Vijer and Illeni, as well as the lesser god Arnum. The lines were soon divided by family lines- Mingan, Sa'ada, Bree, Shin, Liagora, Timeus, Minkah, and Malaquai tipped the balance of power, and later cemented an alliance with the Dark Ones - Aphilam, Daimonas, Darshendros, Sanoci, Uayli, Lisse, and the newly-descended Halloran.
Fearing that the alliance of Chaos and Evil would lead to his overthrow, Chelan stepped into the battle, sending his Defender of the Faith to Mingan and Shin in order to reach an agreement to destroy Caribia, Lisse, and Oraith.
In exchange for this, the God-alliance would be broken, thereby removing the threat to the Godking's throne. Devising powerful magics, the two brothers enchanted a weapon forged by Malu at the direction of Bree with deadly power, and unleashed Rhoslyn into battle. As the Godsbane removed the head of Caribia, raw power surged through the Ascendant Plane, blasting Daimonas's physical manifestation - her last act of defiance against the Godking and her "ally." Weakened, Daimonas was banished by Darshendros after the next kills - he had time only to watch Sanoci - formerly with a domain of Blood - use his power to turn every spilled drop of God's blood into angels and demons in order to replace Blood with Destruction and therefore raise his status.
With the very fabric of reality reeling and damaged, Chelan raised Kuro - Mingan's Defender of the Faith - into godhood, imbued several Lesser deities with power as their followers grew, and released Daimonas, who rose to the most powerful of the Lesser Deities. These acts irreparably fragmented the alliances, resetting the balance of power between the Gods. After an eternal instant of the Gods, save for Pantxike, fighting, allying, breaking alliances, and otherwise competing, the Gods settled into their power hierarchy.
The final words of the war came from the lips of Eyilana, the Seer - The war is not yet over, nor the killing.