Minecraft wiki entry for Defeating_a_Nether_fortress, associated text: Your key prizes are a nether wart plantation and a blaze spawner. There are two levels in a fortress, the corridors and the bridges (described above). The nether wart plantations are by the large staircases up to the bridges. The plantations are usually in an intersection, so be sure to block off the tunnels with a non-flammable block before harvesting the warts. Also take the soul sand, as relying on finding some is not smart. The blaze spawners are on top of the bridges, partially enclosed by fences.