Warframe: The Second Dream (2015)

The Sentient Hunhow awakens from his slumber, seeking revenge on the Tenno for their actions during The Old War. Allying with the Stalker, they seek to destroy the "womb in the sky", later revealed as the Tenno's weakness: a Reservoir on Lua that was hidden within the Void by the Lotus to protect the Tenno from the Sentients.