Zatiel's sword and Nihilak's hand clashed, marking the first real contact between the forces of both sides. A blast of energy that formed cracks in the fabric of reality emerged from that single collision as the Samsara Thearch and Knight vanished from everybody's sight.
The Thearchs, Sacred Kings, and Knights understood that for people of their level, moving up and down would not work in a place like the Emptiness, where there was so little force restricting the collateral damage of their attacks.
Middle Stage life forms unleashed spells that could obliterate everything in a radius of a billion light years. That was enough to encompass the entire battlefield and more, which was why Zatiel and Nihilak moved to a parallel dimension.
It was like a mirror dimension. The Samsara Thearch and the Harbinger of Desolation could hear and see everything that happened in the main plane of the Emptiness, but their fight would not reach it.