Goblins and Spiders and Oooze...oh my!

23, Last Seed 90AN 
Upon delving into the dungeons of the Shadowfell keep, the party of adventurers immediately encounters goblins guarding the entrance. The 7 heroes are able fight their way past the goblins and a well hidden pit trap filled with ravenous rats, and after clearing several rooms of goblins and hobgoblins, kill Balgron the Fat.
Balgron was a particularly porcine goblin in charge of the goblinoid forces on this level. Besides a small fortune of gold, and a magic crossbow, the party found a scrap of paper in his room with the phrase " and life fails in the dark".
Tensions rose among some members of the party over what to do with a goblin that surrendered in the face of defeat. Quinn thought he should be locked up with the other prisoner that was left in the torture chamber, while Eben thought he should be executed. The argument ended, however, when Ivgaar killed their captive. Despite this disagreement, the adventurers pressed on, navigating a series of natural caves. Onset on all sides by monstrous spiders, an ochre jelly and a small hive of Kruthiks, Vythica fell in battle, but was revived by Eben before death could take her. After clearing a small watercave of a lurking blue slime, the party finds a message tube with some intriguing information, including this invitation:
“Greetings, Kalarel. I have recently learned of your activity in the area and have an offer for you. During your time in this region, if you should capture any humanoids, we are eager to buy them. We have duergar allies in Thunderspire in need of slave stock. If you are interested, send an envoy back to me. My messengers will show the way.
Chief Krand of the Bloodreavers.”
The adventurers now have only one place left to explore in the dungeon, and that is behind a locked door....