The light spell can be cast at yourself to restore health. (If you cast it at a monster, it will restore health, but also temporarily stun/pacify it.)
Maybe I should have given the player access to all the spells starting out, after all… When I playtested the game, I did find it rather difficult, but I just chalked this up to being a bad player! 😛 So I left it alone so that other folks wouldn’t find it too easy…