Jacob checked the time he had left before the third wave, feeling like he didn’t have much time at all. He didn’t need to sleep like when he had a body, but his mind did need time to recover. Especially after all the preparations for the first and second wave, he needed some time to clear his mind.

  However, his dungeon needed more work. He had the dungeon fairy pump out enough water for the dungeon to survive for the next day before he returned his attention to the dungeon and its defenses.

  While the strongest of the invaders in the third wave had him worried, he didn’t forget the power of numbers. Compared to the first and second wave, the third wave would have many more creatures in it. From his time back in the game, there were many times when ignoring the weaker creatures caused him to lose.

  At the same time though, the true magic beasts that would come this time were much smarter than previously. The higher level an animal became, the more intelligent they usually were. Having proper magic power allowed these creatures to level up more and faster than their less fortunate cousins.

  These magic beasts were going to be the generals, commanding not only the ordinary creatures but also the lesser magic beasts. They weren’t going to allow the dungeon’s hazards to kill off the animals and creatures like before. Any spikes he made would begin to be flattened, tunnels would be remade or created; the only thing that they would have trouble overcoming were cliffs.

  Even then wind magic had feather fall spells. The generals wouldn’t be sentient, but that didn’t mean they weren’t intelligent. Even back on Earth, animals like honey badgers, dolphins, and pigs were able to perform brilliant acts of intelligence.

  What bothered him the most was that he wasn’t able to figure out what to expect. He knew the AI of these creatures from back in the game, but that hadn’t helped him much so far. Ironically, it would have been much easier to plan against adventurers than animals.

  While he didn’t have much hope with defenses actually killing, they would slow the invaders down. Spikes took time to disarm and tunnels took time to be made—a mistake would cause a cave-in and no one wanted that…

  A cave-in? The idea burned in his mind like a newborn star. In the game cave-ins weren’t that useful and mostly just created a mess. Here, that might be a different story.

  There was no doubt in his mind that there were many magic beasts that could survive the cavernous ceiling falling on top of them. He doubted that any of the monsters of the third wave or even the fourth wave could survive it intact though. Besides, it would create a lot of stone and, in the right place, could force the invaders to waste time digging through the rubble. The invaders that survived, at least.

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  However, he wasn’t sure how to do that. It was possible with complicated traps and mechanisms, but those cost money to create. He didn’t have the funds to create them, and he didn’t feel like he needed to either. He remembered creating cave-ins back in the game, but he struggled to remember the exact method.

  Logically, if he had a suspended stone above a room and cut off the connection to the ceiling, the stone would fall down like a cave-in and bury everything.

  There was a problem with cave-ins beyond the mess they make: these events weaken the stone of the dungeon in that area. Meaning that the dungeon fairy had to go to these places and fix the hidden faults and weaknesses before more messes were created.

  However, if he created a controlled trap like having a massive boulder crush everything, the clean up would be negligible. But how could he do it?

  He recalled some of the movies he watched and gained an idea. It was probably a stupid idea, but if physics worked in this world close enough to what he was familiar with, then it should be alright.

  He did hesitate though as his stupid plan would require him to completely change the layout of his dungeon, which took a lot of time. On the other hand, if his giant boulder trap did work, then he had a viable solution for the fourth wave. He had enough animals right now for the next few floors and layers of his dungeon, so he had no need to try and save any of the new invaders.

  He opened up his map and started destroying his dungeon. His plan was simple: create a large tunnel that spiraled and twisted until it reached near the core chamber. At the end of the tunnel would be a large, smooth round boulder that took up almost all of the space, leaving no room for anything to squeeze past it.

  Normal dungeon stone wouldn’t do this though, it would break too fast. His spikes got damaged just from mundane weight, he needed to make this boulder out of reinforced stone. That way it could survive the spells and destruction it would cause.

  But that only meant it would take longer than it needed. He didn’t have enough time to remove the dungeon. All he could do was create the tunnel and seal off the rest. There wouldn’t be anything in these abandoned tunnels and rooms even if the creatures burrowed in as any path towards the dungeon core would be removed.

  After he mapped out the tunnel and the walls to seal off the dungeon, the fairy got to work. He looked back at the time had left and winced. He should have plenty of time, but time didn’t seem to move right for him. He seemed to have plenty and not enough at the same time. If only the fairy could move while the world was paused.

  After he finished the tunnel, he started working on the outline for the boulder, which was the hardest thing for him to design. He had to create something that would detach when he wanted but finding the right point where something is strong enough to not fall apart by itself was difficult. He wasn’t anywhere close to an engineer or a seer to be able to understand it.

  Jacob decided to hedge his bets and ensure stability instead of speed, meaning that the rock wouldn’t be fully carved from the stone. It was sloppy, but that’s what he gets for being broke.

  He watched the dungeon fairy work as the timer for the third wave ticked slowly down to zero.