Since the spiders here can talk and think, I think it will work.
- Ahem... *trying to imitate the lich's voice as convincingly as possible* The time has come... Open... - the massive door slowly began to open, and a spider crawled out of the room, but saw no one. Then its life was cut short when I jumped down from the doorframe. There was a lever on the wall of the room, which, apparently, opened the door. Dragging the spider's corpse, to avoid unnecessary noise, I close the door by pressing the lever. Now I've reached the altar. I take out the scroll and begin the ritual.