Edenfrost (Edenfrost #4)

As the Russian Civil War spreads across two continents, the siblings, Yuli and Alex, find themselves in an explosive run-in with the soldiers who killed their parents. In a moment of desperation, Yuli makes a blood pact with the Golem and unleashes a violent assault against the attackers. While struggling to survive the bloody conflict, Alex desperately tries to save his sister from her uncontrollable rage before it consumes her whole.