The Nexus (or Imagination Nexus) is the last and eternal source of Imagination, found at the planet of Crux. The Nexus grants a wide variety of powers to those who know how to wield them and according to legend it was used in the shaping of the Universe.
History
Originating in the Primordial Era of the Universe, Figoranol legends speak of its emergence as the event that decided the victory of Figrithen in the Ancient Ith War, after (or during) which Crux and the Kadrus Galaxy were formed around it.
Before humans, elves are known to have discovered the Nexus and become masters of Imagination, however little is remembered of these ancient times at all, other than what is written down in the records and told in the tales of the elves themselves (who are scarce to be found nowadays).
In the case of humans, and the younger generation of minifigures in general, the legendary figure of Aleros the Dragon-Friend is said to have been the one who first learnt the powers of the Nexus and through his teachings, the civilisation of the Figorani was born.
With the aid of Imagination, the Figorani flourished in Kadrus for more than a thousand years and in their time secondary sources of Imagination were formed across the Galaxy (their origin not quite certain), known as the Nexus-Halani (Nexus-Children). However, unlike the original Nexus, these sources were not perfect and waned in time until they were fully diminished (which was an important factor in the downfall of the Figorani).
By the end of the First Great Galactic War, between the Figorani and other peoples, the Nexus was sealed away to be protected from potential abuse. While Imagination still radiated outwards and its powers were not fully taken away, its light would not shine upon Crux for the next two thousand years, after which the Four Explorers, Baron Typhonous, Doctor Overbuild, Duke Exeter and Hael Storm, found it and unsealed it. However, upon doing so the Baron exposed it to Chaos, causing its corruption and turning into a Maelstrom.
Only a small shard escaped, but in the hands of the other three explorers it would soon become the foundation for the Nexus Force, an organisation made to fight the Maelstrom and defend the Universe. The Last Shard of the Imagination Nexus is currently housed in the Nexus Tower of Nexus City, Crux Prime.