Цитадель

From Author Wars - https://authorwars.com/books/tsitadel-2852638.html

Overview:

Title: Цитадель
Author: Алексей Осадчук
Year: 2015
Type: Novels
Series: Зазеркалье / The Mirror World
Number in Series: 2

Variant Titles:

2016. The Citadel