Extinction
A fallen star crashes into Bastion, wiping out all existing civilizations on Rhune and crippling the power of all primordials. Only 10% of life remained after this event, and even less are still around today.
Not much is known about the origin of this star as it's said to have been formed in the blind spot of the gods. While it caused mass destruction, it did ultimately lead to the creation of the Warforged as well as the advancement of the Dwarven race.