Tirith's Bane was one of the Chaos Shards which split apart after the destruction of the Crystalline Prison, it fell onto Terfall, within the heart of Mount Hela were it lay dormant for over a millennium. Until it was found by the Heliens which settled upon on the Mountain's slope, whereby it manipulated the thoughts of their lord Tirith Katanova into betraying his kingdom in pursuit of power. The shard was named "Tirith's Bane" by those who defeated the fallen prince in the war that came after.
When the Chaos Crystal shattered and exploded after Sealiam used the Hammer of Elements against it's holding, the pieces where hurled directly into the mortal realm, strait past the defences of Titan's Palace. Each piece, which where named the Chaos Shards where guided into planets that Xecien believed housed the Web Posts. Tirith's bane was one of those pieces, it was guided directly into the planet Terfall. Where it was planned to land is unclear whether Xecien planned for it to crash into Mount Hela or that it lost control upon reaching Terfall's atmosphere. Either way, when the shard landed into Mount Hela it caused a chain reaction that effected the entire planet to what is now known as the Darkening. The Mountain itself burst into a active volcano that hurled thousands of molten ash and stone into the air which engulfed the entire area in fire and ash. Nothing in that area survived the eruption, which included the Gelldir who had made that province their heartlands. Interestingly, with the eruption of Mount Hela being both natural and magical that it drew in the heat from across the world, which then drained all of the tropical landmass Uthway's warmth however it is also believed that Rioclya's research into the frozen crystal may have also had a factor in Uthway's downfall.
Slow Corruption Edit
It is a lie to think that Tirith's Bane lay "dormant" in the mountain, but more to the truth that it was slowly gaining power through Xecien's spirit, when the Avari colonists, the ancestors of the Helliens first settled on the slopes of the mountain that the shard worked in way, very slowly into their very minds, trying to tempt them into digging it out of the rock and falling to Xecien's will. However the early Hellien where hardy folk who managed to repel the shard's influences for over 160 years until the prince stepped in.