We were crossing a ridge when Corgan was lifted off the ground by something. "Shoot it! Shoot the tyrannosaur!" he screamed as blood streamed from the puncture wounds that had opened up in belly. I fired into the empty space above him to no effect. Then Corgan's ragged corpse dropped to the forest floor, and I was alone. Utterly alone. There was no dinosaur. There was nothing.
A possible answer to what happens to spells when a mage dies. If the spell is strong enough, say and enchantment or other permenant effect, part of the mages spirit may become lodged in the magic. It may be a way for items to gain some kind of intelligence, but a mage who has knowledge of this fact would be very hesitant about enchanting anyone or thing. He might have other plans for his afterlife than counting the change in your bag of holding.
Preists, I think, would have this sort of thing covered.