The Third Calamity-the empty forge
After The Elves left, the Dwarves returned to their holes. Abandoning their cities and their forges, they dug ever deeper in the search for new veins of Aether Stone. No one knows what they found because they were never heard from again. No one who went to explore their homes never returned, after awhile they stopped trying, Then they stopped caring. All they knew was there was no one one left to work the Aetheric Rune Forges so no new Aether gear could be made.
The Fourth Calamity- The coming of the Negamagi.
Centuries passed after the Dwarves left. Man forgot what it was to be. Those in the crumbling cities slowly turned savage while those that had fled to the great mountain flourished. Deep in one of the overgrown cities, an Aethermagi (whose name is stricken from all record) found an unusual phenomena. The places that the Aether came from were filled with another magic, a negative energy. She studied this new power in hopes of bringing back the old days. The Aethermagi and her disciples attempted to solidify this power and got their life force sucked into these negative spaces. This negative energy pushed out sought a new home…the bodies of the stricken Magi. They stood up, themselves…but reborn into forms stuck between life and death. The three of them Christened themselves Negamagi and began to subjugate the savage ruin dwellers.