Bloodguard: The Crimson Oath (Original - strong fantasy vibe)

What if the oath that made you a hero was really a curse?
Kael thought he was becoming a protector—an elite warrior bound to defend the realm from evil. But when he takes the Crimson Oath, he discovers a truth far more terrifying:
The Bloodguard aren't defenders.
They're jailers.
And the thing they've been guarding?
Is starting to wake up.
Beneath the keep, an ancient god of blood and hunger stirs. The Order is rotting from within. And someone—someone powerful—is trying to break the seal that holds the monster at bay.
To stop it, Kael will have to break every rule, defy the Oath, and unlock a forbidden magic that could destroy him from the inside out.
Magic comes at a price.
Blood is just the beginning.
If you crave gritty battles, dark secrets, twisted loyalties, and the rise of a reluctant hero, Bloodguard: The Crimson Oath is your next obsession.