>https://www.warframe.com/pt-br/news/caliban-prime-access-en
So from what I understand this: Erra made Caliban during The Old War, THEN Sentients and the Orokin made his Prime as a joint. The original Venato was a broken off Eidolon limb, Venato Prime was another collaboration with donated Sentient bones.
It notes a common enemy to fight beyond the darkness of Tau. I suppose this means the Murmur? Or the Soulframe things since it's a twin sun system like Tau.