The Night-Gaboon is a very very large snake.  It is a creature native to Reverie.

The Night-Gaboon first appeared late at night, after an evening of tension between the Iicarn and the Flarion.  After the skirmish over Gier had quieted down, the Iicarn were observed opening an aetherhole.  While most of the populace fled the scene, a few intrepid souls stayed to watch.  They observed the large snake emerge from the aetherhole.  Surprisingly, the Night-Gaboon was sentient, as it engaged in conversation with some of these brave souls.  Eventually, it left to go about its business, leaving a trail of miraplasm and mirajin crystals in its wake.

Later the next day, the Night-Gaboon was observed in the company of Dr. Dreamscar.  Again, a few brave souls ventured out of the city to a grassy hill where they overheard the conversation between the snake and the doctor.  The two appeared to be well acquainted.  Those eavesdropping heard hints of the Dr.'s plans to save Valenth by shifting the entire world into a dream state (possibly into the Reverie?) and stated that most people would never notice the difference.