Cast Light makes a ball of light appear above the player's head. It is useful for illumination in the Tomb of the Giants. Outside of this area, Cast Light can be used to dispel certain illusory walls found in Oolacile Township, an area encountered in the Artorias of the Abyss DLC.
Cast Light is one of only three light sources in the game, the others being the helmet Sunlight Maggot and the offhand item Skull Lantern. It can be considered the most useful of the three as it does not require players to sacrifice an item slot and lasts a very long time; however, some players may prefer the Sunlight Maggot if they have insufficient attunement slots or intelligence to use the spell.
Hostile players cannot see the light emanated by Cast Light.