Pretty sure this is the Living Tower Unum. She permenately fused with the Orokin tower via transferrence to protect the people there a long time ago. Now she helps the people of Cetus farm her flesh while keeping the tower defenses controlled.
The date on this picture is 2016-10-09 so Plains of Eidolon wasn't out at the time. The helmet looks like Nyx Prime and the wings are Odonata Prime.
Her weapon has a very caster staff look to it, which fits Nyx's style in a way, but there are no prime weapons that look quite like that. I'm inclined to think the weapon is OC but it's possibly a very stylized Orthos Prime.