This book and Before Dawn belong to the Dawn novel series.
The alien emperor awakened in the abyss of the universe and led hundreds of millions of alien beasts to the earth. These creatures are not blindly murderous, but have some ancient evolutionary mission - they want to transform the planet and transform carbon-based life into a pure "new order" existence.
Humanity's last line of defense has been breached.
At the moment of the decisive battle, the gods sacrificed themselves to open the rift in time and space, and banished the alien emperor back to the ancient abyss to bring a brief moment of respite to the earth.
This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.