Book about character transported to a realm where his written words become spells I remember reading a book, probably 15-20 years ago now, but I cannot remember the name.  It is about a character (some type of English professor/student?) who through some fashion is transported to another realm, where he learns that his written words become spells - and the "Spirit of Entropy" is with him and he can command it with his words as well.

Sounds like The Oathbound Wizard:

Matt Mantrell 20s is Lord High Wizard in world where poems are spells, and oaths unbreakable. After 3 years wait to marry love Queen Alisande, he angrily swears to take Ibile from evil Gordorgrosso. New pals - surly dracogriff Narlh, courtly cyclops Fadecourt, damsel Yverne, well-wist spirits, wee Puck, Robin Hood - join old - Sir Guy, dragon Stegoman, demon Max.

And a quote (emphasis mine):

Narlh frowned at him. "Who's Max?"
"Maxwell's Demon! The one I told you about, the Spirit of Entropy! He controls the organization of matter and energy!"


Inkheart trilogy were everything the character reads becomes true but it takes an eye for an eye