In this quest Kelsey,Ren,and Kishan had to obtain Durga's rope of fire which of course was guarded by all kinds of creatures.
They items they seem usually have a them and since this was a "rope of fire" it would only seem natural that you would have to go to the hottest place on Earth to get it (the center of the Earth).
I loved how this gate was described and that when they got through it trees of flame were all over and that there were mythical creatures who called the place home such as Qilin. Another mythical creature that was met while in this realm was of course the beautiful Phoenix which can be seen on the cover ( his name is Sunset). The next mythical creature that was met (if they even are mythical) were zombies, then came a clan of dark demons known as Rakshas.
After they had just barely gotten past everything they met the key subjects in the realm the twin fire lords.