Three loud explosions that could even be heard by those deeper in the kingdom went off.
Three huge pits remained, even larger than the one made by the compined attacks of the sages. All that remained of all the soldiers of the kingdom was the memories of them in the minds of the living. They were utterly and completely wiped out...
"Well....seems I went a bit too far there". The demon lord said while looking at the aftermath with a stoic expression on his face... internally he felt a bit embarrassed.
The demons just looked at him with an expression that said "why act all cool before when you didn't even damage the grass only to do something like this a while later?!!"
"Cough, now summon some men to come and take over the land and imprison the humans as usual while we'll continue". As if trying to escape his embarrassment he quickly flew off towards the next kingdom right after giving his orders.
The demons just sighed, did what they were told and followed after him....
By the time the rest of the demons caught up, most of the day had gone by.
"What took you so long, you kept me waiting here for hours". The demon lord said with rebuking look on his face completely disregarding that he was a lot stronger than them so he obviously could travel a lot faster than them.
The demons not only had to run on land, except for the dukes of course. They also had to go through a forest with beasts too, since it stood in-between the two kingdoms. Although the beasts weren't strong enough to pose too much of a threat, they were still enough to delay them.
"Since you'll are clearly tired, we'll camp here for the night and destroy the kingdom tomorrow". The demon lord said, much to the relief of the soldiers.
As the demons rested, news of the total annihilation of a kingdom without even a chance to retaliate spread to the other kingdoms. This time it was even worse than before, the humans couldn't even resist and it was all done by a single demon.
Even more appalling news was the disappearence of the sages. To top it all of, studies on the hero summoning ritual weren't progressing very well. All in all, the humans were screwed and they knew it.
.....
Next morning
"Well this is odd". The demon lord said looking at the site in front of him, or more clearly, what wasn't in the site in front of him.
Unlike before, no army was present, even though he knew that the humans already knew his location. Even more surprising, every village, town or city they passed by as they went deeper into the kingdom looking for the army was basically deserted.
They caught an oldman in one of the cities and after an interrogation realised why most people were gone. News from the capital had spread around the whole kingdom through transmission magic during the night. It was one simple statement..."If you don't want to be killed by the demons, flee the kingdom!"
Some were skeptical but when they saw that their neighbours were packing, they did the same. Of course there are always the idiots who think they are special who remained. They'd be caught by the demons the next day and be enslaved or killed as they drowned in their regrets. Though not all of them were idiots, they simply couldn't flee on their own and were abandoned. These involved the elderly, little children and the disabled.
The royal family and his army with their families were the first to flee. They had made an undisclosed deal with a neighbouring kingdom were they'd merge their arms together. They couldn't do it in their kingdom since the demon lord was too close so the time might not be enough for the other army to come over.
The demon lord was so amused by their plan that he gave them a whole week to finish all their preparations after the merger. Though it was mostly because he wanted to oversee his men as they take over the two defeated kingdoms.
And so, humans now only had six kingdoms on the continent while the rest were now part of demon land.