Trapped?

Ready for whatever might come his way, Leon steadied himself, his senses heightened for any sign of the Goblin King or other lurking dangers.

The sudden disappearance of the Goblin King, coupled with the fading of the portal behind him, deepened Leon's frown of concern. This development was highly unusual. Unlike the system-generated dungeon he was accustomed to, where portals could appear and disappear at the system's whim, portals within traditional dungeons were meant to be stable. They typically remained open until the dungeon's complete clearance of beasts, at which point they would dissipate along with the dungeon's structural collapse. The premature dissipation of the portal was not only abnormal but also alarming—it suggested something far more troubling.