Minecraft Mod Light Level. This mod adds /gamerule mobspawninglightlevel that allows changing the light level at which hostile mobs can spawn. Normal mode displays the the block light level reaching the block.
Shows light level 0 as red so you know where you have to put light sources to prevent mob spawning. • type /trigger togglelightlevelchecker to toggle your light level checker! Mobs can only spawn at light level 0.