SET - 555TH, THE MOTHER OF NIGHTMARES
Though the eldar all have differing remembrances of the time before Time (TBT), all have a memory of avoiding Set. There are no memories of fighting Set, because Set consumed any eldar he encountered. There are only a few who stood up to Set and survived.
The 1st instance was when Demos and Gorgos were forced to unite to cast Set away from them. They were losing and neither could fathom their impending loss. So, they united into Demos-Gorgos. They casting of Set "as far away as possible" created the infinite layers of the Abyss as Demos-Gorgos reinforced layers upon layers of protection... to buy time and to keep Set away from the Gate of Chaos.
The 2nd instance was when Pha Rann, Asmodeus, and Demos-Gorgos united to bind Set in slumber. They could not kill Set for fear of destroying the Gate of Chaos (Gorgos was okay with a universal reset by the way).
All other eldar, upon encountering Set, were consumed or so twisted by Set that they may as well have ended. That's all Set wants to do. Like a child destroying another's sand castle at the beach, Set's thrill and all of his might are bent on the single purpose of ending everything until only he remains. What Set would do in that result, no one knows. Gorgos speculates, during his few rare lucid moments, that Set would then create his own sand castle only to knock it back down.
In physical form, Set is the 555th subnexal plane of the Abyss. Because a mortal mind cannot understand an entire throneplane, Set appears as a titanic dragon covered in half-open eyes rather than scales. The eyes, where visible are bloodshot and yellowed. It is said that each eye follows a single disciple. It is also said that when you experience a feeling of dread, or cold fear, that one of Set's eyes has focused on you. He is worshiped by the Slaadi, the Hags, the maedar, the illithids/mind flayers, aboleths, and creatures who cherish dominion over the minds and souls of others. Because these are sentient and powerful races, their worship of Set intrudes into his dreams and keeps him strong. Additionally, because Set's dreams spawn monster races, those races become part of Set's dominion even though Set himself is not active. Any chaos-twisted creature of tendon, eyes, and bone - unless created intentionally by some other power - came from Set. This is how monsters can spontaneously arise upon the land of otherwise peaceful and civilized lands.
Set is important because of the Tanian Spear Prophesy. Set is also important because of the story told in Dar Tania 2: Set's Dream where the Slaadi are introduced. Moreover, the Gardenkeeper medusa - Syliri - is viewed as an avatar of Set by worshipers of Set. Though this story is partially told in Set's Dream, in the Time Before Time (TBT), the maedar enslaved the medusae race and experimented on their petrification powers to enhance them with Set's Dream. Syliri led a rebellion of genocide against the maedar. It's likely a few survived in other realms and how they covet Syliri.
Most worshippers of Set believe that, by creating cataclysm in Set's name, they can interject themselves into Set's slumbering awareness and be granted power. It certainly seems to work. Though illusionary, the powerful effects of Set's Dream can make a person drown in the air (they think they're immersed in water), see friend as enemy, and - as that power increases - the wielder of Set's Dream can change the attributes of creatures caught in it. Using Set's power can come by touch, sight, or area effect. It generally has phases of power based on how strong the wielder is:
- Illusionary - the affected sentient creature is aware that something is wrong. For example, Syliri senses that something that isn't real and knows it... like Bruce appearing as a murderer
- Delusionary - the affected creature is falling to the dream and can't differentiate reality anymore. Syliri sees someone trying to kill her and responds accordingly
- Altered Reality - reality actually begins to change for those in the dream. Bruce actually is trying to kill her
- New Reality - the dream becomes reality. Bruce is actually a murderer even when the dream ends. Of note, this is how medusae' petrification gaze works by creating a new reality.