Eternal of Spring
Most commonly, Arhallogen is called the Spider King (although gender has little meaning for this powerful creature, it is usually addressed by male honorifics).
It is also occasionally referred to by other Eternals by a name that sounds like a sequence of quick clicking noises - noises commonly produced by Arhallogen, its heralds and its spawn.
A swarm of poisonous insects and arachnids that speak with a single whispering voice; a monstrous spider-like, scorpion-like horror, all pincers and deadly stingers; or sometimes an insect-like vaguely-humanoid shape in cobweb robes and an iron crown, bearing a poisoned glaive.
Arhallogen is an inhabitant of the Spring Realm, and part of the family of Eternals that are the most alien to humanity. It seems to be fascinated by the ways living things prey on and compete with each other, especially the adaptations and natural qualities that let them hunt, kill and consume prey - or that let the prey fight off their predators.
Unsurprisingly, the Spider King rates venom as one of the most potent tools that any living creature can employ, and is delighted to encounter new poisons.
During the Winter Solstice 378YE, Arhallogen was declared to have the enmity of the Imperial Conclave. The enmity was later removed, but not before the eternal launched a vicious attack on the Hall of the Worlds with venomous heralds.
This dark Eternal encourages competition between living things, not so much out of a desire to see death or conflict but apparently from an urge to see living things survive and prosper. It offers a number of boons, many of them violent, and often involved with crushing weaker prey or poisoning stronger creatures to make them weak.