The black energy was split by a single wave of Theo's sword. It didn't have any strength or skill behind it. There was only a huge amount of energy from Theo's body. The energy utilized the illusion and the Reality Authority applied it, causing the black energy to be truly split.
Of course, the black energy kept sucking the Magic Power that hit it. Unfortunately, Theo could see that his attack didn't get absorbed completely. He knew that the original Theo's power was overpowered, but it wasn't undefeated.
It was clear from the previous attack that the energy had an absorb speed. As long as he could calculate the energy and time to completely absorb an ability and use something beyond it, he should be able to win.
With that thought in mind, Theo started moving forward, avoiding the black energy.