Reg never expected the Black Dragon Guild to attack them, nor did he anticipate the power of the Black Dragon's Thunder Primordial Energy Array. His Defensive Sword Array was strong, not easily deciphered by just anyone, even if he had conjured it hastily.
Attacked by the Black Dragon, he didn't get angry. After all, he had attacked the Black Dragon himself before. It wouldn't be fair to allow only the Black Dragon to be hit and not to hit back.
The force of the thunder had been weakened. The Thunder Primordial Energy Array, which obscured half the sky, possessed a destructive power on par with a forbidden spell.
The intent wasn't to kill them, probably just a lesson.
Or perhaps to test his strength as a Half-step Divine Spirit.
Streams of black-and-red Thunder Source Energy continuously plunged down from the Array, bombarding the five city lords.