I was stuck on this bug for the longest time. I couldn't wrap my mind around why my blast bullets went straight through walls. Silly me forgot to put a rigidbody component on the spell's prefab object. The rigidbody component is the Unity provided code to make physics interaction possible. Now that I'm using it here I have blast spells that hit walls and play an explosion animation before disappearing. I also changed the cooldown rate so you can't let out an endless stream of spells. Now it's just a matter of making the other spells and making something to shoot at.
