The book series starts with a young guy trying to master magic in the hut of his master. He's been trying to light a candle with his mind for months but failed miserably. Next thing he knows a 'demon' appears, gives him some pointers, and whisks the guy away on a series of adventures across parallel universes. The tool used for this was referred to as a 'd-hopper', or dimension hopper.
In these parallel universes the competent use of magic is rare and the guy soon becomes the best magician around, even though he has little to no skill with it. Adventures ensure, friends and enemies are made, and the guy's magic develops.
One universe the story leads us to consists of a world of ugly-looking large snails, and disguising themselves with magic, the protagonists are forced to walk incredibly slowly.
The series is a trilogy (I think), it's a comedy and I remember reading it in my early teenage years
Does anyone have a clue what it is? I've wanted to re-find this book for at least a decade, if not more!