It became clear that Copper was in someway connected to the murders, probably the murderer himself. The party asked around as to where he might be after not finding him at The Red Hammer. A few patrons mentioned that they'd seen him going to the Tain Foundry, and eventually it was found that he had lodgings there. It was getting very late, so they it was decided that a rest was needed at the inn, before proceeding to investigate.
They were woken early by Dandy, with some grave news. He hurried them over to the Red Hammer, where a scene of carnage was within. The corpses of Shadowblack, Ash, and an unknown Warforged lay strewn on the floor, each with various body parts missing. In Ash's case, his head had been removed. After investigating, the party found traces of copper in the wounds, and assumed this had come directly from Coppers plating.
They quickly headed for the foundry. After finding Copper's small room with help from Molric, a hidden door was eventually found, that headed underground. Within, various horrors were found. The party had to navigate a trap that with a thin wire that pushed them down a corridor as blades sliced at their legs. Daellin managed to walk straight into it, but eventually Smith disarmed it. Then, a number of constructs awaited them in the next room, such as living limbs, moving chains, sentient boulders, and their master, a Ravid. These were eventually defeated, then Daellin managed to get himself electructed on another trap, this time on a door.
Finally they found Copper. Behind him was a juggernaut of a construct, made from the Warforged body parts of his victoms, including Ash's head. Copper started raving about how he had made the purest, untainted life, not tainted by the flesh. He was clearly mad, claiming to have made a perfect being out of the imperfect victims. After he was done talking, he unleashed a mass of magic missiles, and began to fight, using more magic. He did not pose a massive problem, and Selene d'Lyrandar had the insight to start attacking the juggernaut before it activated. It was a tough fight, with Elias Minch breifly going down, but in the end the party were victorious.
In the aftermath, it became clear that Lord Slogar d'Cannith had some involvement in this as well. He admitted it smugly, believing himself untouchable. He claimed he supported Copper in his quest as a means of seeing what the experiment would yield. The party realised it as Slogar who organised the assassins, but chose to let it slide rather than attempt to take on House Cannith.