Elemental: Fallen Enchantress - Legendary Heroes Developer Journal

There's a new developer journal for Legendary Heroes over on the official Elemental forums, in which Stardock CEO Brad Wardell takes something of a spoiler-driven approach to explain how the team is "concluding the War of Magic". I'll quote from the non-spoiler section:
Rise of the Channelers

However, one day, a powerful Sorcerer was born who could channel the magic from the crystals scattered throughout the world. This allowed for some fledgling kingdoms in the western part of a continent called Anthys to resist the Titans. The Titans, recognizing the growing strength of their foes, used their magic on those races of men under their thrall to create new races that men now collectively call (The Fallen).

Many of these new races used their newfound abilities and power to flee Anthys entirely and exit our story. However, three of them went on to become lethal servants of the Titans The Quendar, the Trogs, and the Urxen. The Quendar were the Titan's most trusted servants. The Trogs their loyal soldiers and the Urxen their tireless workers.

Still, the free Kingdoms on the west of Anthys, led by Sorcerers who rivaled the Titans themselves and aided by Tandis the Arnor continued to grow. The Titans, therefore, sought to open a gateway back to their homeworld to bring reinforcements. When word of this reached the Kingdoms, they launched an all out attack to stop it.

The Cataclysm

In the great confrontation between the combined might of the Titans and the entire host of the West, the gateway device was destroyed while in the midst of opening a portal and the resulting blast was so vast that the seas poured separating the remaining east and west from one another. It also laid the lands in waste. This became known as the cataclysm. The Titans were gone but so were the Kingdoms.