Tenebris Conquest by James Silvestri
From out of nowhere, a massive force of eldritch and savage monsters invades the continent of Dissental, ending the lives of all they encounter and laying waste to the lands they rampage through. Without warning, the apocalypse materializes and rends the world.
Priests of the Pantheon attempt to bring hope and salvation to those tormented by the monsters, but politics and full-scale war fuel additional tribulations across suffering nations.
As a group of young men and women flee from the destruction of their isolated arctic village caused by the monsters, a renowned military academy elsewhere deliberately seeks out the beasts, actively making their extermination a priority -- and gaining knowledge of dreadful truths along the way.
The apocalypse also brings more than just the monsters. It brings their blood, radiant in otherworldly power. The magical superpowers that their blood can bestow on humanity also exacts terrible costs on their users -- but, some sacrifices are worth their price.