Fortress of the Burnt Warlord

Publisher's blurb:

Magma oozes and bubbles beyond the walls of this towering fortress, which sits high above cliffs of stone and jagged rock. Murder holes bring death upon those who would scout beyond the lava, and ritualistic shapes written in blood can be found, painted at the feet of their leader's throne...

The entire structure has been carved into the mountain; the remaining stone used to extend the fortress, in towers and parapets, out over the lava itself. Perhaps, only those accustomed to heat can survive here - or is there some form of magic, keeping the inhabitants within alive?