Minecraft wiki entry for Phantom, associated text: Phantom spawning is similar to other monsters spawning: the spawn location must have a light level of 7 or less, and spawns are limited by the monster population cap. Phantoms are also subject to a density cap of 5. Phantom spawn attempts are made on surface blocks throughout the same spawn radius as other monsters. However, when a phantom spawn attempt succeeds the phantom appears somewhere in a 21×15×21 cube centered 28 blocks above the player instead of at the block where the spawn attempt occurred.