The group ventures to the stairs leading towards the third floor of the Keep. They check carefully for any traps, and Dorrin - with his stone sense - spots several steps that function as pressure plates, triggering darts to fly out from concealed holes. With Dorrin’s help, Halbard guides the group around the traps and up to the next floor.
The room that awaits them is mostly bare. Four skeletons stand around the room - one in each corner - and each skeleton has differently colored gems for eyes. When a light is shone through the eyes, arcane symbols are illuminated, carved into each of the gems. In the center of the floor, a chalk square is drawn; the square is divided into four equal, smaller squares, and each of those is subdivided into four equal, smaller squares (for a total of sixteen squares). There are four symbols marked onto the floor, matching the symbols hidden behind the skeletons’ eyes.
Between Sulyex and Quaesitor, the group quickly realizes this is a logic puzzle to solve to gain entrance to the main body of rooms here on the third floor. Sulyex leads the group in completing the task, and the door opens to reveal a long hallway with a closed door about halfway down on the left side, and open archways on the right and directly ahead.
Coratana quickly teleports ahead to the open archway and finds a room containing half a dozen unresponsive humanoids, chained or restrained in some way. He teleports back to the group, with this information, and they slowly begin to scout out the rest of the rooms. Tension grows as they explore but find no sign of their foe.
As they approach the farthest, darkest corner room, they hear a slight shuffling and the sound of metal sliding on metal. They approach cautiously, prepared for battle, but rather than Blackthorne, they find Neva, the dragonborn they were summoned to this world to find. He is in rough condition, missing the middle clawed finger from his right hand, and obviously showing signs of injury. He is reluctant to allow them to examine him, though Sulyex persuades him to try some Holy Water. Though it causes no damage, Neva describes a mild burning sensation from where it sits on his skin… something he finds himself both craving and fearing. His movements expose what he had been hiding from them before: multiple bite marks from where Blackthorne had been feeding on him. He surrenders himself to the party, drinking the Holy Water in an attempt to slow or halt Blackthorne’s influence on his body and mind. The group leaves him tied up, finish exploring the top floor, and are flummoxed at the lack of Blackthorne (though they are concerned about the scattering of bone piles around the rooms).
They eventually gather in the sparsely-furnished central chamber of this floor, where Halbard and Sulyex start taunting Blackthorne, shouting out insults in an effort to garner his attention. They hear a soft thump behind them, and when they turn to look, they see Blackthorne’s form shimmer into view as he drops his invisibility from where he has dropped from the ceiling to land directly behind Dorrin. They see him mumble something under his breath and Dorrin’s eyes glaze over as Blackthorne dominates him.
Dorrin turns against his friends as Blackthorne summons piles of bones into skeletal forms, including a large skeleton-like with an exceptionally long reach. Audir casts a Daylight spell that sends Blackthorne fleeing into the darkness in the next chamber over, and Coratana chases him down. The Boneclaw protects another entry into that room and prohibits other party members from following to aid the Hexblade. Coratana faces Blackthorne one-on-one but falls quickly to the vampire’s necrotic power. Kaira feels his partner’s death and tries to dash into the room, unable to dodge the strikes of more skeletal warriors summoned by Blackthorne. The dragonling also falls to his death.
Meanwhile, Halbard and Quaesitor manage to strike some sense back into Dorrin, but the Boneclaw and Skeletal warriors hold them at bay. Blackthorne uses his necrotic abilities to strike down Sulyex and bring Halbard to the brink of death. As the battle goes on, a sickly-green mist begins to rise and thicken, diminishing visibility, and when Quaesitor falls unconscious and doesn’t rise again, concerns about poison in the mist also rise.
The tide of battle truly turns when Blackthorne manages to get a clear view of Audir and successfully dominates her. Before all is truly lost, time seems to freeze. The group finds themselves in a void of pure darkness, and out of nowhere, Owen appears. He is bedraggled and visibly bloodied, coughing blood into his hand and struggling to maintain his balance. He asks them not to speak - there isn’t much time. He claims to ability to give them a gift; he calls it the last gift he can give. He summons an orb of glowing light from within his chest, pulling it out gently as tendrils of light try to linger, stretching back towards him to try to hang on. He takes a deep breath and exhales onto the orb, splitting it and sending the sections evenly toward each of the party members. They feel a restoring warmth, and then they blink and find themselves back in battle with Blackthorne. A gentle force raises up their bodies and sets them gently back onto their feet. Their minds are their own. Their bodies are restored, well-rested as though the day were only just beginning.
A look of awful jealousy and fury crosses Blackthorne’s face as he takes in their restored forms. Utilizing their new strength, they quickly strike him down and destroy his minions. Their strength comes at a cost, though… Kaira wasn’t restored, and his body has disappeared; the trail of blood stops abruptly at the threshold of an arched doorway.
After the intensity of battle passes, the group also notices that their Sanctum pendants are now mundane, dead metal. Whatever heat or vibration of life had been inherent in them before is now gone.