Core of Ysenn

The Core of Ysenn, otherwise known as the Heart of Ysenn, is Ysenn's plane core, world core, world heart, or commonly referred to as plane heart. The core has been sought after by Eldiceir, Eidolon Wright of Lusters for millenia, due to her home plane, the celestial homeworld requiring constant world cores in order to sustain its celestial power. Her, Fjagnarh, Eidolon of the Slain and her sister Avihjya, Eidolon of all that Lums were one of the many groups sent to procure cores, but has been unable to find it due to lack of resources after spending the past nine millennia locked in war with Ysenn's native and later arriving inhabitants.
After realizing conquest was unsustainable and being left by Avihjya who could no longer leave Ysenn to die, Eldiceir changed her strategy to secret excavations by a network of paladins, spies and Leanroh loyalists, and funding and manipulation of organizations to search for it. It was located in the depths of the Mines of Syglykh until it was found by the scholar Ynnfelin and his assistant, which turned out to be Krurymtir, Eidolon of What Can Be Coveted in disguise. After finding the core, Krurymtir mortally wounded Ynnfelin, who later bled out in the mines, and took the core. Leaving Ysenn with no plane heart.
Due to the lack of a core, Ysenn has grown progressively weaker in several ways over the recent century, especially in temperature, causing regular famines, particularly during colder seasons. This was discovered by a group of solidars who have been traveling around Ysenn preparing to find and return the core to its rightful place.