The Changing Land by Roger Zelazny

This book has the grandest theme & the most strangely-named demon. The name is Melbriniononsadsazzersteldregandishfeltselior.
Zelazny includes a touching love story between Queen Semirama & a tentacled semi-elder-god who lives in a cesspit below Castle Timeless. The Queen is hard to like since she's indifferent to prisoners chained in the dungeon & only talks to her slave when she has to work. She'd been raised from the dust by the evil sorcerer Jelerak in order to communicate with the ancient denizen of the cesspit, a source of tremendous occult power even tho he resembles a gigantic, smelly octopus.
The theme of The Changing Land is the death & rebirth of the universe & the meddling of the Elder Gods in human, elvish & demonic affairs. Some of the characters, such as Dilvish the Damned & his hell-horse, Black, spring fully-formed onto the pages. They were actually born in earlier short stories, collected in Dilvish, the Damned. It might be easier to read Dilvish, the Damned before diving into The Changing Land because the latter fantasy has many characters. There are gods, demi-gods, semi-demi-gods, black & white magicians, heroes, elves, mechanical horses, demons & at least one Queen. A couple of them change bodies at least once, which doesn't make it any easier.
Castle Timeless is the center of the action, the goal of every power-hungry sorcerer who has a staff to wave at its numerous demons. Its corridors are a constantly changing maze. The land surrounding it is a mad god's dream of exploding volcanoes of mud, hedged with flame, alive with winged monkeys.
Zelazny had completed his 5th Amber novel by the time he wrote The Changing Land. There's an Amberish glow to the mutating landscape & castle of this book. Once you have the characters straight, it's a wonderful read. No other author has the chutzpah to take readers thru the Death of the universe & back out again thru the next Big Bang.--E.A. Lovitt (edited)

This book is part of the "The Dilvish Stories" series.
Here are some other books from this series: