Minecraft wiki entry for Mob_farm, associated text: One of the most popular overworld designs for a general mob farm is based on a tower of spawning pads that are periodically flushed with water to push the mobs off so that they die from fall damage. The water comes from a central pillar of dispensers and observers that cascade a clock signal between platforms. This type of farm is known for its high production rates, simplicity, reliability, and ease of build. Examples are provided in the videos below for Java and work in 1.16.