Unlike his first impression of the castle which was grand and majestic if a little over done, the cavern he was in now seemed like a long forgotten corner of the world filled with naught but darkness. There was no sign of anyone having ever crossed the various tunnels, nor that they had been used for any purpose.
If Lex had not followed the dwarves here, and clearly felt the increasing Dragons Might, he may have assumed that he had teleported to a tunnel in the middle of the planet that had never been discovered. Even the increasing temperature felt like to him that he was moving closer to the layer of molten lava deep under the surface of the planet.
As he made his way through, following not but his instincts to guide him, Lex felt something he hadn't in a long time. He used his thumb to wipe his brow, and discovered sweat. It had been a long time since he sweat naturally. Considering his cultivation, there must be something extremely unusual about the temperature.
