The party faced a choice: retreat behind the temporary safety of the hallway doors to gain a quick rest or push forward and hope that a quick strike would win them all of the keep's defences. Fearing that this opportunity would not present itself again they opted for the later.
While Nenia went back upstairs to seal the upper access door, Ethan bee-lined for the front portcullis mechanism in an effort to seal out any exterior devil forces. He arrived to find two duergar crawling under a half-open gate. He determined it would take several seconds to manually turn the mechanism and thwart the creatures swarming the gate. Braddoc followed to lend his axe to Ethan's cause and Helia engaged a group of duergar advancing toward them from another door.
Meanwhile Delian was forced to run and defend the rear portcullis leading to the lava bridge. On the far side of the formidable metal grate raged a pair of hulking Shocktroop Devils bellowing for someone to open the gates. Delian was nicely holding his own against three Legion Devils when a fourth opened a door on the far side of the room and the Chain Princess Baelzra once again joined the fray.
Realizing that smashing the chain of the portcullis control would be much faster than trying to crank the winch, Braddoc switched places with Ethan and, with a mighty swing, brought the gate crashing down upon the now-halved duergar beneath it. Both Braddoc and Ethan then moved to assist Helia back along the hall.
Things were looking worrisome for Delian. Ethan and Helia decided that two Shocktroop Devils bringing pain upon their heads was a more serious threat than the troop of duergar they were fighting so they left Braddoc surrounded and raced to Delian's aid. While Braddoc occupied his foes, the rest of the party started to eliminate the threat near the lava gate.
Eventually the tide was turned and Baelzra disengaged to return to her room where she closed the door behind her. Two Hellcallers appeared and attempted to block the path but pint-sized Helia simply moved through them, shrank the locked door, and burst through mere seconds later with weapon at the ready. To her surprise, there was no sign of Baelzra. The macabre room within held a large bed, a chained succubus, dozens of instruments of sex and torture, and a ring of runes etched into the floor at the foot of the bed. Thinking that Baelzra was up to some trick, Helia moved into the room only to quickly become nauseous. After a very brief search she was forced to retreat and re-engage the Hellcallers.
It didn't take long for the remainder of the duergar to be slain. All would have been quiet if not for the bellowing of the devils outside the lava gate.
During a few minutes of respite the party determined that Baelzra's room was unhallowed ground. Any time spent within it brought with it the massive risk of being overcome to some nefarious end. The succubus in the corner simply laughed at the weakness of the party. Not to be defeated, Delian tied a rope around himself and moved into the room. Unfortunately he was not successful at finding anything except for the remains of one of the small cube objects in the middle of the rune circle. He too fled the room feeling extremely ill. An arcana check from the doorway revealed the runes on the floor to be some sort of teleportation circle. They deduced that it had been powered by the smashing of the small cube.
Eventually Ethan moved in and was able to find a secret lever that slid the bed back to reveal a chamber beneath it. He moved below and found a chest and wardrobe containing magical items, riches, and potions. Unfortunately, as he tried to exit the room, he was overcome by the vileness of the room and fell into a deep sleep. He comrades pulled him out with the rope.
Meanwhile, Braddoc found three prison cells containing 18 more humanoid prisoner. Oddly, the didn't react to their rescuers. They simply remained expressionless and still as if in a trance or as if they were waiting for something.
Feeling momentarily safe, the party gathered themselves and began to discuss their next moves.