The Green Portal

As the alchemists explored the entire battlefield, searching for and healing survivors, Melina and I went back inside G'Henna's tower after Sage Astra asked for our presence.

The sage and Yuki stayed on the 99th floor, where the demonic portal was located. 

After I died for a few minutes during the battle, it seemed like the gem-link that sealed the portal stopped working. Thus, many powerful demons began to enter our world through it, leading Yuki, Sage Astra, and their team of mages and samurai to deal with them.

Fortunately, the gem-link returned to its normal state and re-sealed the portal right after I came back to life. However, Sage Astra said in her message that the energy produced by the gem was strange—though it wasn't dangerous.

Since we couldn't go to the 99th floor from the top, considering the terrace on the 100th floor didn't have a way to go back down, Melina and I had to enter the tower from the bottom and make our way up.