The cufflink.
For a moment, the world narrowed to that single, gleaming point of silver in Caelan's mind. He saw it on the floor of the workshop, felt the phantom weight of it in his palm. He had called to it with his blood, with a binding spell that should have ripped it from the very fabric of reality to return to him.
And the spell had failed. Snapped.
Now he knew why. It was not destroyed. It had been found. Held by a mortal. The magic would have registered it not as a lost object, but as a possession, shielded by the will of its new owner. A piece of evidence.
The pieces clicked into place with the cold, final sound of a tomb door sealing shut. Someone had been in that workshop after he and Lucien had left. Someone had found the cufflink, understood its damning power, and delivered it to Elias Wren. A perfect, elegant piece of treachery.