I had to rewatch the Celebrimbor/Sauron scenes. I'm fascinated by the spectrum of Aule's apprentices, their failings and their approaches to creation. Annatar watching Celebrimbor living in Feanor's shadow, recognizing what he's willing to sacrifice and then pushing him past that - perverting the act of sacrificing one's own time/effort/flesh into just his own flesh and forcing someone else's time and effort is an interesting take. To quote LotR and The Last Unicorn -
"The Shadow that bred them [orcs] can only mock, it cannot make: not real new things of its own."
"Real magic can never be made by offering up someone else's liver. You must tear out your own, and not expect to get it back. The true witches know that."
Adar has begun to knowingly or unknowingly mirror that by sacrificing his children.