(I was not the original creator of this build, I just turned it into a schematic. Cubix Creations is the owner of this build)
Cubix Creations Dark Room Spawner Schematic file, it's really good for early game XP. Watch this video for further information: https://www.youtube.com/watch?v=dOqC17l_Gqw
The lectern is for multiplayer servers, and it should say something involving the fact that the farm is most efficient at 4 render distance, and to not shift, as that will make creepers explode.