The original Theo thrust his spear while Theo waved his sword.
Theo applied the illusion to cut the original Theo into two, but the energy for the illusion ended up getting sucked into the black plate above him.
In the end, the two weapons clashed with each other. Since they were only powered by the Magic Power, their clash only caused a small shock wave.
Theo clicked his tongue and struck him a few times, only to be blocked by the original Theo's spear.
If this continued, the black plate would have finished sucking all the energy from the Ascension Step, allowing the original Theo to use the next move.
Hence, Theo immediately used the Reverse World, his second original ability. The Reverse World allowed him to change the character of everything around him, especially the black plate.