Minecraft wiki entry for Blaze_farming, associated text: These are possibly the most difficult to build because the open fortress will also spawn wither skeletons, normal skeletons, zombified piglin, ghasts, and magma cubes. Building an open-fortress design meant solely for blazes is impractical if you have an alternative, but if your nether fortress does not have a blaze spawner, or you accidentally destroyed them, an open fortress farm is your only option. Here are the basic parts: