Degenerate fate casts us together once more, Guardian. How I have missed the thrill of pitting my Cabal against your unyielding tide of Lightbearers, truce or no.
But it is in the spirit of Zavala's newfound truce that I offer you news delivered by my Cabal scouts. My forces recently recovered the remains of a Human male on Nessus, vivisected almost beyond recognition using Hive techniques and tools. Our science identifies the unfortunate as your Warden of the Infinite Forest, Osiris.
While I will not divulge the details of our confirmation methodologies, rest assured they are thorough and accurate. This news no doubt will shock you, given that you are also in possession of another Osiris still clinging to life. But it is not him, despite the confirmation of his identity performed by Ikora Rey. Her admiration for her old mentor has already clouded her ability to recognize an imposter once, and it appears to have happened yet again. It is not custom among the Cabal to allow even a respected leader a 3rd chance to fail their people.
I don't know what purpose the Witch Queen could have in giving you a comatose husk wearing your dead ally's face, or what threat he may become: a listening device, a future mole, a living bomb? But understand this: when Savathûn brought Xivu Arath to my doorstep, she did so wearing the mask of a trusted advisor. What you hold in your Tower is no treasure, and I have faith in you among your kind to handle this problem as a Cabal would.