You'll also be able to upgrade player stats such as total health, armor, ammo capacity, movement speed and item drop rate from enemies. (waytoomany.games)
The other spells can only be used once before they are gone but can be collected again from items dropped by the enemies. (theswitcheffect.net)
I often found it was a better option just hoping a random item drop would provide something better than going through the hassle. (nosleepgamer.com)