Three days later, Castle of Black Iron...
A figure like a streak of light flew through the skies of Castle of Black Iron at a terrifying speed. The figure was so fast that, from nearby, the naked eye could not catch it at all; only from afar could one see a faint gray line flickering in and out of sight as it cut across the sky...
"Rumble..." It was as if lightning had flashed through the air. On the ground beneath where that figure passed, a bare stone hill over fifty meters high was blasted apart amid the lightning, scattering rocks like arrows across a radius of over half a kilometer. After the explosion, all that remained of the hill was a massive crater over ten meters deep and wide.
"Rumble..." "Rumble..." "Rumble..."
The thunderous booms rang out without end. With every deafening blast, the hills of varying heights beneath that flying streak of light exploded one after another, leaving enormous craters in the ground. That flying figure was practically like a supersonic bomber—merely passing overhead, it plowed a gigantic trail across the land.
Heller, Edward, Agan, and Aziz stood atop a peak of the Divine Mountain in Castle of Black Iron, watching the ravaged land more than twenty kilometers away.
That land had been newly generated within Castle of Black Iron over the past two days. Located beside the Divine Mountain, it covered a total area of 2,000 square kilometers and had a surface layer one thousand meters thick. It had been created specifically as a training ground for Zhang Tie to hone his combat skills within Castle of Black Iron.
With Zhang Tie's current combat strength, ordinary combat skills could naturally be honed in the Soul Tribulation Realm. However, combat skills such as kinetic energy attacks, especially those