Cave Illuminator

The Cave Illuminator when placed down will slowly light up caves (similar to Illuminating Powder) below the block, by default it has a 64 block range but this can be changed via configs. This can be picked up with a pickaxe and the light sources will stay. The Cave Illuminator does not need to have visibility to the sky to work.

You can also change the colour of the lights the Cave Illuminator places down by right clicking it with a coloured Illumination Wand: