In the end, it didn't take long for Billy to figure out the gimmick of the door. Basically, they just had to pile the corpses near the door, and they eventually would become dust. The dust would fill the symbols in the door little by little, and eventually, the door was opened. Unfortunately, it was impossible to see the guardian from outside since the dust was pretty thick inside, and it was like a curtain… On the other hand, the monsters stopped spawning when the door opened, so the group could rest a little bit.
"Once we get inside, watch out for your backs," Billy said. "The crystal is probably conserving its energy to help the guardian, so it might make the beetles spawn to help the guardian."
"Yikes… that is kind of scary," Lily said.
"If the guardian attacks, don't take any chances and repel them by using your best skills," Billy said. "Let's win this, only losing a few pieces of flesh here and there."
Although Billy said that as a joke, everyone took that very seriously since he wasn't the type to joke. Billy just shrugged while watching them gulp. At least that will put them on their toes.
Once they entered the last room of the dungeon, the door closed. That was the sign that they didn't have any chance of leaving unless they defeated the guardian. The dust began to settle down, and then Billy felt a presence above them. Ten meters above them and in the ceiling, he found the core of the dungeon. It was on the size of a person, and it was emitting a red light. It didn't seem that sturdy, but Billy decided not to test its sturdiness… nor did he have the time for that because the ground began to tremble, and then a massive figure began to approach.
The monster was on the size of a truck, so being hit by that wouldn't be much different from being isekaied to another world. Billy didn't want to test that theory, though. He was happy with his current life… Regardless, the grey and frail carapace had been given place to a dark one that emitted a weird glow. It was probably some sort of metal… and Billy recalled seeing some of that in the warehouse of the guild. The monster had eight paws, two frontal and two on the back, but the creatures could walk just using the ones on the back, and then frontal ones had claws that were made of that dark metal.
The beast tried to cut in half the front line with those claws, but Billy and Alexander repelled those with Light Spear. A powerful sound of metal colliding echoed through the dungeon and made everyone's ears ring. Fortunately, they succeeded in repelling the attack.
Kate and Lily fired their projectiles at the enemy's eyes since it was the only unprotected place, but the beast blocked their attacks with one of its paws. Before they could try again, Natalie dashed toward the enemy and swung one of her swords. The enemy easily repelled that one, but Natalie used the impact to jump and propel herself upward and pass by the monster's defenses. However, when she tried to attack, the enemy headbutted her before she could swing. Natalie blocked the strike with her swords but was sent flying backward while spinning. Somehow, she landed on her feet, but her arms were still trembling due to the impact.
"That metal is too powerful… focus on dodging, or your weapons will end up breaking," Billy said.
If that were to happen, it would be disastrous, but despite saying that, Billy didn't look that worried, so his friends realized that he was up to something.
"I will retreat for a little bit, so cover me," Billy said and then put his spear away and then pointed both hands toward the monster.
In the next moment, Billy created a ring of fire around one of the monster's arms. While the black steel was covering most of its body, some parts like the joints were unprotected. Otherwise, the beast wouldn't be able to move. Regardless, the monster tried to extinguish the fire by swinging its arm, but it didn't work. The beat also tried to hit it against the ground, but while the first try decreased the flames a bit, Billy's friends attacked the monster's face and stopped the beast.
The ring of fire was getting close to the flash, and the beast began to tremble dust to the pain… he wasn't holding back and was using his rings, so something like that was to be expected. The guardian couldn't move or attack while Natalie and Alexander were trying to pierce its eyes and while the ring of fire was melting its flesh.
In the end, much sooner than anyone had predicted, the arm of the monster fell on the ground, and the creature grunted and trembled in pain.
"One down, three to go…" Billy said.
Natalie suddenly began to attack even more fiercely. Billy realized that one of the areas that were bothering her was the one he cut off, so she decided to overwhelm the beast with sheer speed. As if that wasn't enough, she was also targeting the joint of the arm. Each strike of her made some blood of the monster gush out of the wound. The beast began to walk backward to gain some time, and Alexander noticed what Natalie was doing, but he couldn't do the same against two arms.
In any case, Kate and Lily began to circle around the room and then began to attack the back of the monster.. That formation was a bit weird, but it was working.