City of Heavenly Fire (The Mortal Instruments #6) by Cassandra Clare
ΕRCHOMAI, SEBASTIAN HAD SAID.
I am coming.
Darkness returns to the Shadowhunter world. As their society falls apart around them, Clary, Jace, Simon and their friends must band together to fight the greatest evil the Nephilim have ever faced: Clary’s own brother. Nothing in the world can defeat him — must they journey to another world to find the chance? Lives will be lost, love sacrificed, and the whole world changed in the sixth and last installment of the Mortal Instruments series!