I'm guessing this book was written in the early 80s because I read it in college or right after I graduated in 1984.

It was about a wizard/mage(?) who is kind of like an itinerant one. The only huge plot point I remember is the end--he somehow sets up a huge explosion to take place and in the very end he is leaving the kingdom in a wagon (driving it) and you learn that in the explosion he lost his leg.

I really would love to find this novel --and the author--so I can see if there were any more books about the wizard.

Does anyone have any ideas?

Might be "Wizard Spawn", the second in a trilogy (Sword of Knowledge) mostly  by C.J. Cherryh.  Maybe not - published in the late '80s i think.  Anyway, "wizard" is an alchemist who is accused of magic and leaves town in a wagon  just ahead of a mob - aided of course, by the explosion.  Don't recall him losing a leg.