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."