Progenitus

Progenitus is the Avatar of the Alaran Worldsoul. It is a being of enormous power and worshiped as a Hydra-God. According to the Anima's visions, it had become bored with creation and unleashed five storms to consume it: Wildfire, Earthquake, Windstorm, Flood, and Void. Its actions were stopped by the elf Cylia who forced it, using a poisoned dagger, to assume the form of a five-headed hydra avatar to stop its plans. This tale is likely an apocryphal account of the events that took place during the Sundering.

Due to the lack of blue and black mana in the Valley of the Ancients, the place where Progenitus rested, two of its heads withered away, and the hydra was doomed to slumber under Naya's soil for many years.

Millennia later, it appeared to Mayael, the newly appointed Anima, and asked to speak with Cylia, unaware that she had perished millennia ago. The image of Progenitus was soon co-opted by Nicol Bolas, prior to the Conflux, to tell Mayael to build up an army to counteract Sarkhan Vol's invasion of dragons, thereby creating a greater expenditure of mana to fuel the Maelstrom.

Regardless of Bolas's plans, the reunification of Alara reawakened Progenitus.