Overlord Volume 4 Chapter 4 said:
What exactly was this Overlord of Death attempting to do?
The lizardmen which were nervously watching this Magic Caster let out a panicked sound altogether. At this moment, an enormous hemisphere-shaped magic array approximately ten metres in diameter expanded outwards with the magic caster at the centre.
A blue and white radiance floated on the surface of the magic array, with semi-translucent markings which looked like it could be words or symbols. Those semi-translucent markings were rapidly changing, and at any given moment none of the words were the same.
Being unable to understand what exactly it was, Zaryusu felt confused.
When a magic caster was casting magic, one would not project it into the air like he did with the magic array. The opponent’s current movements were already beyond Zaryusu’s area of knowledge, therefore he turned to the female lizardman here who was the most familiar with magic and asked:
“What exactly is that?”
“I-I don’t know. I cannot figure out what that is either—”
Crusch’s reply was a bit terrified. It looked like she was even more frightened because she possessed knowledge about magic yet was unable to understand that behaviour.
Just at the moment that Zaryusu was planning to comfort her…
Not knowing if the magic had successfully activated, the magic array broke apart, becoming numerous light particles flying towards the sky. In the next instant— like there had been an explosion in the sky, the particles spread out—
And the lake… completely froze.
Not a single person could understand what exactly had happened.
Shasuryu who was a tribe leader with outstanding qualifications; Crusch who had extraordinary druid powers; even Zaryusu the traveller who had seen much and had a wide breadth of knowledge. Even these individuals, who within lizardmen history could be considered to possess miraculous abilities, could not immediately comprehend the current situation.
No way of understanding why their own feet were inside ice.
Before long— after enough time had passed for the brain to accept the situation before their eyes— a crying rang out—
Every lizardmen— indeed, everybody let out a lamenting cry.
Even Zaryusu was the same. Crusch and Shasuryu, and even the most courageous Zenberu, were no exception. As if terror crept out from the depths of their souls, everybody could not help but scream.
This fact laid out before their eyes was simply too terrifying. The lake, which absolutely would never freeze over, which had never frozen over ever since the moment of their birth, was apparently frozen solid.
The lizardmen frantically lifted their feet. Luckily the layer of ice was not thick, and broke immediately, but the broken areas immediately froze up again. A chilling cold vapour came from underneath, making it painfully obvious that this sight was not an illusion.
After Zaryusu agitatedly clambered up the mud wall, he immediately surveyed the surroundings, then was stunned into silence by what he saw from his widened point of view.
Everything in his field of vision was completely frozen over.
Indeed, it was inconceivable to imagine that such an enormous lake would be entirely frozen solid. However, this radiating ice which covered everything in sight was also reality.
One corner of Zaryusu’s mind was also worried about the situation of his fish farm, but now was not the time to be worried about such things.
...
"Please wait a minute— will this ice melt away?"
Regardless of who won or lost, with the lake frozen, the lizardmen would find it very difficult to survive.
"... Ah, I almost forgot."
Saying that he had forgotten. This airy attitude of Ainz surfaced in his reply.
"I only wished not to dirty myself with the wetlands mud as I walked, which is why, after returning to the shore, the magic effect will be dispelled."
"What!"
Zaryusu and Shasuryu were shocked into silence, and questioned if they had heard wrongly.
He froze the lake simply because he did not wish to get dirty?
This was no longer at the level of being hard to believe. The opponent's strength was simply too overwhelming, even able to easily change the force of nature, and furthermore for such a silly reason.
So it turned out that they were opposing such a powerful being— Zaryusu and Shasuryu both felt the same fear as a child would being all alone.
"Until next time, lizardmen— 「Portal」."
Feeling that everything that needed to be said was said, Ainz stretched out his hand and gave it a gentle wave, and a dark hemisphere appeared in front of the throne. Next, he jumped into that darkness.