While you were busy with changing, you start to hear something even though no one else was around you, meaning that the voice was disembodied as you became able to hear him without seeing him. "Yes," the voice says, as you could feel the sharper teeth in your face finish growing while you were still standing on all 4s.
"We both know you have no way of escaping this, human mortal," the voice says, while you were struggling with your transformation, and wanting all of the pain in your body to stop which was never going to happen. "I have been stuck in that relic for a thousand years, after a group of adventurers have defeated me. Today, is the day where I become reborn, but I need a vessel to get my body back. Luckily since you didn't know about me, and aren't related to the heroes that defeated me, you are just what I needed."