Green Demon Blood Essence Crystal

The group of demons then crashed into an island, dying in the process as their Demon Cores had been stolen. They were then ganged up by the Monster Geckos, tied up before being dragged by a team that carried them into a secret tunnel nearby, eventually dropping the bodies at a certain chamber. 

All the bodies dropped here had lost their Demon Cores, the only injury on their body. It was apparent that all of them had been killed by Hazak. 

The massive cavern was a bait to lure in as many demons as possible. No matter what, the Monster Geckos living in the place were tremendously weak. Even the Monster Gecko King was nothing but a mere Tier 2 being in terms of strength. 

Considering how even the weakest demon that explored the labyrinth was a Green Demon, having strength at Tier 3, they were just small fry. But of course, Feifei had planned this specific place to be the bait that would give her as many demon corpses as possible.