The Elemental Sisters

There's a long lost legend lost among the magicks. That there once was the Elemental Sisters the most powerful immortals among the magicks. They could control the elements split between them. They were most beautiful and most magical. However, they were hardly ever seen. They only showed themselves in times of pure danger and sorrow. But one day, the magicks were up against their most powerful, and dangerous enemies, yet they never appeared. The magicks were almost all killed off, only few managed to escape with their guardian beast.
Those magicks and guardian beasts went lost to memory. Only their ruler, Nytrik, the empress of the magicks, knew of their existence. She also knew what had happened to the Elemental Sisters.
Who are the Elemental Sisters? Will they return? If so what does it mean if they do?