When the component Light is mixed with the shape Projectile, it creates a spell that can replace all other light sources. The lights produced are white.
The lights can also be placed by other spells, if the spell targets a block, a mage-light will be placed at that location. If the spell targets a player, the player will be given a status effect that makes them a roving light for a time.
Mage lights can be cast on all blocks and will float beside, under or over whatever block the spell hits. The lights can be broken when hit. Unfortunately, when placing any block where a light previously was, before being broken, the block disappears and the light comes back. The light can be broken again but nothing can be placed where a light has been placed. It has been found that, if a door is placed where a light used to be, it still disappears but you can see the outline of the door if you look at it correctly. Also, if you walk at it you can not go through the door even though it is invisible; makes for a good prank. When the invisible door is outlined and you right click on it, the invisible door will make the sound of opening a door and then the door will disappear for good. To get the invisible door back you have to break the light, and then place the door back down. Also, when the invisible door is opened and it disappears, the light that reappeared when you placed the door will turn brown. It's unknown why any of this is, but hopefully it has been fixed or is being fixed right now.