A long-dead powerful wizard at the Unseen University and founder of the wizard order the Ancient and Truly Original Brothers of the Silver Star.
He made a study of the Octavo and the Eight Great Spells and discovered that while most spells will say themselves when the wizard who has memorised them dies, this is not true of the Great Spells. Changebasket wrote a book stating that the spells would instead take refuge in the nearest object. This knowledge led Galder Weatherwax to attempt an alternate method of retrieving the lost spell from Rincewind. Rather than chase Rincewind across the disc he would send a magical arrow to his location, which upon killing Rincewind would be able to absorb the Spell and return to its point of origin.
It almost worked.