Since Ben (Justin H. Min) is dead, we don't get to see much of his powers. What little we do see is thanks to Klaus (Robert Sheehan) manifesting him. However, we do know that he's able to produce cthulhu-like tentacles from his body (earning him the nickname "The Terror"). While it's not entirely clear if it's meant to be one of his powers or not, Ben plays a big part in getting Vanya to stop the oncoming apocalypse 2.0. He's able to bypass her energy barriers and enter into the inner corners of her mind, allowing her to reach inner peace. With the end of season two producing an alternate timeline where a very alive Ben is part of the Sparrow Academy, hopefully we get to see more from him in the future.