The defense system had some traps, as well as puppet-like contraptions. Tang Yu was interested in some of the features.
Stone Sculptures: Build a group of stone sculptures and place them all over the castles. When enemies approach, the stone sculptures will activate and turn into all kinds of the beast to attack the enemy.
Corridors/Staircases: All the corridors and staircases in the corridors are equipped with changing functions, so only the ally could go through the castle unhindered.
Attacking Flowers: The flowers in the castle garden will be aggressive and attack the enemy like a storm.
These systems weren't as strong as No. 1 and 2. And this upgrade was used to guard the castle so he couldn't make use of it for things like diggings and stuff.
Tang Yu understood, if the enemy really attacked the front of the castle, these safety measures were useless. However, as the territory grew, the survivor's population would also increase. There will be bad people mixed with ordinary survivors.
With the castle's expansion, No. 2 can no longer cover every part of the castle, and most of his followers won't be around the castle most of the time—usually, only Elaine and Winnie who lived in the castle with him. At the same time, the others prefer to stay in the patrol headquarters. Tang Yu didn't understand their reason, but probably it's to drill the patrol members.
Just like the territory map. It's impossible to observe it 24/7. There would be inevitable trouble coming up. Now, the system gave notification to unimportant things.
To avoid the eardrum bombardment, Tang Yu had given some points to ignore the system notifications. In any case, these measures were taken against thieves.
Handing out a few spirit stones, the defense system was finally built.
Two stone statues appeared at the entrance of the main castle. One was a bird with two pairs of wings. One of its claws hooked up in front as if it was going to attack. The other one was a crouching tiger, ready to leap as the King of the Jungle.
Looking at the other side, not much had changed. Yet he could notice some of the flowers had become more vivid. Or rather, they had become a demonic poisonous plant.
Why did he suddenly look forward to when the castle is attacked?
...
"A level 4 castle can now build two fortresses." Tang Yu muttered, his eyes falling on the top item on the build list. The cost of a single fortress was 50.000 spirit stones. Aside from that, he didn't need to spend anything else but spirit stones.
"According to the instruction, after the fortress is built, it will add another kilometer in the territory area. And then, various buildings can be built."
Right now, the territory covers around 5 kilometers. Although the sub-territory is smaller than the main territory, it's more than enough. He can expand the area by upgrading the fortress.
"But I'll have to postpone the territory construction for now. Where can I find a suitable place to build the sub-territory?"
He had to save the sub-territory construction for later, and he shifted his attention to the last new feature.
Personal Domain.
The description text is very short. Tang Yu searched for a while and felt this feature couldn't be completed within the territorial range. So he called No. 2 to guard the castle and left the territory.
The breeze was gentle, but the wind was hoarse and dry.
The difference between the wilderness and the territory was growing bigger. Just like a Lord that just stayed in his castle all year round, he felt that the territory's climate was much more comfortable than in the wild. With this in thoughts, maybe there's a lot of potential with his future real estate business plan?
A rare experience happened. A demonic beast caught his scent and punched, only to be snapped into two by a single punch.
Tang Yu closed his eyes. Sure enough, he felt something different.
"Is this the Personal Domain?"
The scope was small, no more than a hundred meters. He tried to build a building. This time, the way to operate it was different from the territory. Rather than opening it from the construction system panel, he meditated on it. He was aware that he could build it or not in his mind.
So he tried building something, but all he could build were mostly defensive buildings. However, building a system building in his Personal Domain requires an extra cost.
The spirit stone price remained the same, but the other materials cost slightly increased. It wasn't expensive, but Tang Yu felt something else from it.
He headed to the opposite direction of the territory and walked out another kilometer or two. As he had expected, the material cost had increased. "Is it because I'm further away from the territory? So that means aside from spirit stones, the farther I am from the territory, the more expensive it will be."
Tang Yu pondered, "Maybe I can use some local materials?"
He put this thought on hold. Instead, he experimented with an alternative option. And the cost for construction of a temporary building had reduced a lot. After a while, a gradual realization emerged.
"A temporary building can last for three minutes, and it requires about a tenth of the original spirit stone cost, and it didn't need other resources."
In terms of cost alone, it was definitely cheaper than building a proper building.
But… the limit was only three minutes, what if he built ten, or a hundred?
Smirking, he opened his eyes and looked towards a certain spot in the ground in front of him. After a few attempts, Tang Yu had become familiar with his Personal Domain and could construct a building with his eyes opened.
"Rise!"
A 3D model, from the building structure to a solid-state, took only a few seconds.
Tang Yu circled the arrow tower for a closer look. It was just a temporary building. Apart from the slightly lighter color, there are no many visible differences from the real one.
A demonic beast howled. It had caught the scent of delicious human flesh and rushed forward.
Right now, the muzzle of the arrow shot out an energy arrow. Still running, the demonic beast's body burst open into a red mist. Compared to the original building, this temporary arrow tower wasn't that bad.
Swish!
Opening the building panel, he flipped the page to the Defense building list. Looking at the unlocked defensive buildings.
"Arrow Tower, Cannon, Spell Tower…"
Aside from that.
Anti-aircraft Cannon (Primarily used in dealing with aerial creatures).
Beam Towers.
Spike Traps.
Scorching Jets.
...
After the upgrade, there were more unlocked defensive buildings available to build. Without mentioning the spirit stones used in building them, the damage was insanely similar!
Now, he was truly an architectural ability hunter!
But…
"It feels like I'm walking down further and further on the path of spirit stones warrior."