Light Level Overlay Reloaded Mod 1.8, 1.7.10, 1.7.2 visualizes the light levels emitted by torches, glowstone and alike directly on top of blocks, this is helpful to quickly identify areas where mobs can spawn. It shows the light level of the airblock above the block the number is drawn onto, this is the block that is considered for mob spawning, light level 7 or below allows mobs to spawn.