The rest of the waiting time went peacefully for Naomi. There was only one accident that ended in the death of one adventurer. Naomi lost her cheerful demeanor for the whole day, but it wasn’t the first death in her halls, and she learn how to deal with it.

  Just before the construction of the new floor began, disturbing news reached the oasis.

  “Sir. Could you repeat what you just said?” She approached one of the officers from the caravan, who was visiting the tavern.

  “Good day, Dungeon Mistress. Are you interested in the rumors of undead invasion?”

  “Yes. What can you tell me?”

  “Regretably not much, Dungeon Mistress. When we were departing, the first news was reaching the town where we were. Most likely it’s just the usual thing. Every few years, necromancers amass enough zombies and grow bold enough to attack fortifications.”

  “How bad could it be?”

  “Not much. Depending on how big the armies are and how smart necromancers are…

  “Smart necromancers. That is a good jouke.” The adventurer next to him laughed.

  “...They could take a small fort or outpost. It happens sometimes. Later, we are taking them back.”

  “Dungeon Mistress, if I may add something?” One adventurer spoke.

  “Please do. I need to know what is happening.”

  “I’m from the north, Dungeon Mistress. Despite how it sounds, my people see those attacks as an opportunity to get rid of the cultists.”

  “But a lot of the people could die.” Naomi protested.

  “True. But looking under every rock and bush to check if they are not hiding there is difficult and time-consuming. When they attack us, we don’t need to look for them, just kill them.”

  “Dungeon Mistress.” The officer from the caravan spoke. “Like I say, I don’t know anything more beyond that it’s happening. But maybe the general of paladins knows something more?”

  “Thank you. Both of you. Your idea is indeed good. The general should have the most accurate news.” Naomi thanked them.

  “General, thank you for taking the time to talk to me.” Naomi smiled.

  “Dungeon Mistress. Answering your question is part of my duties here. The messenger mentioned that you were interested in what was happening in the north?”

  “Yes, general. I heard the rumors.”

  “Regretably, Dungeon Mistress, I don’t know anything more than that. I, too, received news that cultists besieged some of the citadels in the north. But how serious a threat they pose is unknown for now.”

  “Can you tell me how bad it could be?”

  “The news I received mentioned attacks in multiple places. That suggests this attempt at invasion will be similar to those from the past. I could surprise you, Dungeon Mistress, but usually those attacks end in stalemate. And when winter came, necromancers fell back.”

  “But zombies should be tiresome. Ok, necromancers probably need to take breaks to recharge mana or to rest. So why do fights stop? Not that I’m not happy for that, but I don’t understand this.”

  “The answer is simple, Dungeon Mistress. It’s the mud. When all the snow melts, it leaves pools of water, and the soil is soaked in water to the brim. After a day of trampling the ground, you will get swamps. So they retreat sometimes completely, sometimes just outside the mages' and trebuchet range. But swamps are also impossible for defenders to cross, so the whole siege ends in staring at each other.”

  “That is something I wasn’t expecting. So this attack is dangerous, but cultists don’t know what to do, so everything should be fine?”

  This story originates from Royal Road. Ensure the author gets the support they deserve by reading it there.

  “Yes, Dungeon Mistress. All fortresses have enough supplies for half a year, sometimes more. So even if defenders become encircled, they will survive until reinforcement arrives.”

  “You could be called?”

  “Yes, Dungeon Mistress. But don’t worry. Even without me, the sun elves will protect you."

  Naomi takes a deep breath and looks into his eyes.

  “I know, and I’m confident in my dungeon defences. General, if the worst happens, you and your men have my blessing to travel wherever you will be called to defend the weak.”

  “Dungeon Mistress, your blessing means a lot to me and my knights. We would not disappoint you. However, can I have a question?”

  “Yes.”

  “If I’m guessing correctly, you, Dungeon Mistress, are blaming yourself for this attack. Is that true?”

  “Yes, General.” Naomi sighted. “What you all told me, cultists are arrogant and proud, and my golem orcs, or sun elves catching their spy, could make them angry. But they can’t reach me or this place, so they attack people in the north.”

  “Dungeon Mistress, they will use your name as an excuse for their atrocities, but the truth is the opposite. Thanks to you, this attempt at invasion could be repealed much more easily than those in the past."

  “How? I didn’t do anything.”

  “You do a lot. I will need to spend hours explaining everything, that's why I will mention the most obvious one. The grand magic.”

  “Oh.” Naomi understood immediately.

  “Yes, Dungeon Mistress. While the number of mages proficient enough in the grand magic is not high, there are at least a few in every castle on the border, and more people are learning how to use it.”

  “Understud. Thank you for easing my worries.”

  “I’m glad to help, Dungeon Mistress.”

  Two weeks later, when Naomi began designing the fourteenth floor, she was still thinking about what was happening in the north. And most importantly, how she could help. She wasn’t allowed to introduce weapons from her world, and frankly speaking, she was conflicted in that matter. She agrees with the gods that it will cause more harm than good, and truth to be told, most of modern Earth's weapons were so sophisticated that there wasn’t a way to replicate the production process in this world. However, on the other hand, a few tanks or jets will easily deal with archlich and cultists in the blink of an eye.

  “Maybe they even surrender when they see them,” Naomi said to herself. “Tempting as it is, I don’t have a factory to build anything like that. And no one will know how to use them properly. So what else? Food, medicine, swords? No, they have it, or caravans will bring them. Wait, caravans. There are not enough caravans, and animals can’t travel during winter, but golems could. Ach, but using golems will be difficult even when people learn how to use them. Then let’s try to build a steam carriage.” She immediately began her work, and in the blink of an eye, she had a frame ready.

  After some trial runs on different terrains, she became disappointed. On solid and rather flat ground, it works perfectly. It was approximately three times faster than walking, at around twenty kilometers per hour. But driving it off-road was a nightmare. Any larger hole or loose ground, such as sand, caused the vehicle to get stuck. Naomi briefly thought about using caterpillar tracks instead of wheels, but abandoned the idea. She will need to add complicated suspension, and the whole vehicle needs to be easy to build and repair. Naomi also realized that her plan had one more fatal flaw. Necromancers use swarms of zombies. They could use them to stop the carriage and pry the doors open to get inside, even if the entire structure is made of iron.

  “Airplanes and airships will be nice, but they're too complicated. Let’s see what other methods of transportation we have.” She pondered and looked through the list of vehicles and animals used. When she found her answer, she laughed for a while.

  “Yes. Let’s see if I can pull it off. This will be filarius if someone from Earth sees them. And cultists will run when they see them walking.”

  She immediately began working. The driver can’t be outside, so she doubled the size to fit him and the boiler operator inside. Then push a little more to make room for cargo or people. It wasn’t much by Earth's standard, just one ton of goods or a few passengers. Here it will be like one big heavy horse-drawn carriage, but without animals, and that could travel in the middle of winter. The next part was the most important one. She needs to make it as simple as possible. The locals knew a lot about foundry and forging, but they had no real industry. They do everything by hand and on demand, so anything that will need machining needs to be replaced. Also, the boiler can’t run on fire mana stone alone, because they're too rare for that. She used a set of five arrays powered by standard mana stones to boil water in the tanks. And because of all the snow and ice in the north, replenishing water will be easy.

  When everything was ready, she covered the inside with wood and animal fur to insulate the interior.

  “Now, it's time for the floor. I need something like a test track to test them, and also to make a place for people to learn how to use them. It needs to be on the surface because I need to simulate the northern climate. My biggest floor is six kilometers across. If I squeeze it and elongate, I could get maybe even triple that length. Nice for a test run, but it will be too easy for invaders to cross. I will need a sort of labyrinth for that.” She was thinking aloud. “Wait, instead of making a road straight across, I could make it spiral.” She managed to cover fifty kilometers of the path that way. The edges of the road were surrounded by cliffs and deep ravines, making it impossible to pass. But because the road was too straightforward, she added two bridges and one tunnel in the middle to make it more interesting. Inside the tunnel, she placed a fort where adventurers could get rest and replenish supplies. Along the road, she placed various golems to hinder adventurers' movement forward. There were orcs, wolves, bears, and even gorillas disguised as yeties. Finally, she covered everything in thick snow and ice, and made the weather harsh. Temperature below freezing, strong wind, and falling snow were the basic settings.