As Thuk approaches, one of the splotches of blood running along his arm lights up, evaporates, and the portal once again opens for five seconds revealing a cavern of some sort. It is hard to tell what is inside without a light.
Lightfeather approaches, and the same happens to her. A few drops of blood along her outreaching forearm lights up, evaporates, and the portal opens for five seconds to the chamber inside some sort of cave.
There seems to be no other exit.