story identification - What book has a man in a world on the brink of an ice age with a wizard mentor?

I'm trying to find the title of an old fantasy book I read at least 20 years ago, but I have very little to help identify it.

Obviously I don't remember the author name, I think it was written in the 80s or late 70s.

It was a classic premise with a modern day man from our world, transported to a fantasy setting. The world I remember was on the brink of an Ice Age and the main character and wizard mentor found a keep to save the human race.

In the keep they found ancient machinery to produce light, warmth and food.

The magic in this world was glyph based, using the true meaning of word to change reality. Obviously the main character becomes a magician even if not really that skilled.

I think there was also a triangle with the main character, a princess and a dead husband who was not so dead after all, but it's all really foggy.

There were at least two books in the series.

Answer

This sounds a bit like Time of the Dark by Barbara Hambly. It is the first book of the Darwath trilogy and was first published in 1982.

• Story is about Rudy and Gil from our world who meet a wizard (Ingold) from Darwath and are transported back to that world



• Darwath is on the verge of an ice age and civilisation their under siege from the "Dark". The Dark are a mysterious race of monsters that appear in the night & cold and fear the light & fire


• Rudy discovers that he has the ability to become a wizard and is trained by Ingold


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  Rudy also has a love affair with the "widowed" queen of Darwath (Minalde).

  
  

  
  

  In one of the later books (3?) it is discovered that the King is not actually dead but was captured by the Dark

  
  

  
  


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  Rudy & Minalde cannot be together due to politics and religion (the Church persecutes wizards)

  
  
  


• The survivors of the Dark attack are led by Ingold to an ancient keep which provides shelter, warmth & food via mechanisms the survivors do not understand


• Gil becomes a warrior & Ingold's lover

I can't recall the details of the magic system exactly, I don't remember glyphs, but there were elements of power via true understanding of reality. And Rudy was an artist in our world, so that may be related too.