Beneath his feet was the torn up ground he expected. Past that though?
The area had become a crater.
Zack felt positive that nothing would've happened, after all, he was still standing on the ground. The only issues with that line of logic was that it was ignoring what he had done and where he was.
To begin with, the stone ground of Crystallia was far sturdier than the common dirt of the surface. And rather than only using the High Grade Novice Tier Ardor contained within his chestplate's Ardor Crystal, he used his own Adroit Tier Ardor too.
The gap in energy intensity was immense, but it was impossible to notice due to the game's current limitations. So, Zack couldn't have known that would've happened..
But the crater was relatively flat, save for the area where he stood. It could still function as a proper arena, but Zack needed to do some sculpting first.