Minecraft wiki entry for Blaze_farming, associated text: In this design, the blazes are pushed by pistons when they touch the pressure plates, which condenses the blazes into the grinder. The grinder, like many other farms, is triggered by a button, which suffocates the blazes until they are down to a half of a heart, allowing for players to kill them in one hit. This design also includes an option to trigger lava flow on and off, allowing to stop blazes from spawning if desired.