The Era of Tower Defense: I Have Super Enhancement

The Blood Moon descended and the magical world was invaded by dark and evil beasts – Werewolves, Evil Spirits, Vampires, Hellhounds, Nine-Headed Serpents…
More than half of humanity perished; the rest could only hide within a few major cities in order to survive.
In order to defend against the beasts which attacked frenziedly, humans began to build various tough walls and defense towers with different functions under the guidance of the “Architects”.
After paying a huge price, the humans and the dark creatures entered into a stalemate. The walls and the towers had become gory monster meat grinders. In order to weaken the monsters, every human, once they came of age, would be teleported to various parts of the world to collect materials and set up bases. The humans’ bases of operation also gradually expanded.
Right after he was reincarnated into this world, Thomas was teleported to the wilderness. He was not even an Architect yet. Just when he was about to be overwhelmed by the monsters, he acquired the Super Enhancement System!
By collecting the cores of different monsters, Thomas could activate various cheat codes in the system.
[Fire Tower has been upgraded to Serial Explosions Tower. It might is comparable to a Tomahawk Missile.]
[Beginner-level Shooter Tower has been upgraded to Elf Shooter Tower. The shower of arrows will turn any monster into a pile of minced meat instantly.]
[Earth Wall has been upgraded to Magical Diamond Wall. It can reflect any form of magic.]
While others were still scavenging for resources and struggling to survive, Thomas kept building all sorts of tall towers and thick walls. Monsters were killed by him one after another.
Henceforth, humans saw a ray of hope for the first time. Thomas would surely use his system to lead the humans in annihilating the beasts and seizing back their homes!