You will need to locate a monster spawning block, but once you do, you can build around it and make a pretty powerful xp farmer. Monster Spawner Farm. The spawner area can be recognized by a large quantity of cobwebs. If you haven't gotten to The End yet, then you can do a monster spawner farm. This is the new design for a skeleton/zombie spawner-based XP farm, re-designed to fix broken mob elevator.It is based on the new mechanic of water elevator using bubbles that go up from soul sand in water. Once a spawner is found, there are a few things that need to be done before starting the farm. The cave spider spawner will be in the center of the cobwebs. Before starting the farm, you will need to find an abandoned mineshaft that contains a cave spider spawner.