Entombed is host to many magical and wonderous phenomena, some of which can be controlled with spells. Depending on your character's job, you may have many spells at your disposal. Spells require magic points to cast.
Spells are powerful offensive and defensive tools. Some encounters may be very difficult without the help of magic, so be sure to experiment. Some spells have side-effects that aren't immediately obvious.
To find your character's spells, first press C to go to the character menu, then select jobs, then spells.
Some spells can be cast out of combat. Press M to get a list of possible candidates.