Fantasy book about dual magic where the protagonist learns his dreams are actually real [duplicate]

Question

I read a book a long time ago that I'd like to revisit.

Main plot involves a protagonist that learns every time he dreams he's actually living a dual life in a monastery. Every dual person who sleeps in one world wakes up in another and has dual magic. Life/death or knowledge/ignorance or fire/water. Protagonist chooses life/death and one his hands is dead as a result. He realizes the language he studied in what he thought were his dreams is real and can speak them to other magicians that live in the two worlds.

I remember that if someone died in one world, they would lose their magic and have to live out the rest of the other life in the other world.

If I had to guess I read it about 20 years ago, though I do not know the original publication date. I have a vague memory of the cover being of one or more people underground. If memory serves the fire/water magic worked where if the caster summoned a lot of fire then water would also appear to 'balance the scales'. There was a scene where the fire caster summoned fire in an underground tunnel and a nearby reservoir tried to flood the tunnel to compensate.

Answer 1

This might be Pawn's Dream (1995) by Eric S. Nylund.

The Google Books blurb says:

Roland Pritchard's dreams of being in a monastery in a fantastic world offer him an escape from his lonely existence as a convenience store clerk, although the monk has dreams of his own, nightmares of a future world.

It appears as though the book had different covers in the U.K. and the U.S.: