Having infused two Laws, now two remain, Logan felt a headache coming on for the next one, instinctively wanting to choose the Thunder and Lightning Laws.
However, although his Thunder and Lightning Laws had reached Great Achievement, and using them for the Seal was within easy reach, the key point was that the Thunder and Lightning Laws were laws of attack, not a means of defense!
Once used for sealing, it would only instill the Seal with a murderous intent. If it were to be repelled by other Laws, creating chaos, wouldn't that cause the Seal to explode on its own?
But on the other hand, Logan believed that the best defense was offense, and furthermore, thunder represented Heavenly Dao, possessing a deterring power unlike any other Law.