She can control the Exo, the Cloud Striders and the Vex (they are all Vex related). She could be the most powerful being in the universe with and infinite army of robot robot, Light user human robots and cybernetically-enhanced Human.

>>531858836
Maya Sundaresh has the potential to become one of the best final bosses in history. First of all, I love her design. Then, at last, we have an evil human as an antagonist. Finally, the Vex are going to become really relevant and not just background mobs.

I think they introduced her really well, first in Lightfall and then in Echoes. And her mastery of the Vex may finally make it possible to have a Vex saga.