Bloodroot

A war between the mages and regular humans ended with the regular humans acquiring the power of magic. Despite overcoming this hurdle, they possessed no army capable of beating the mages.
Luckily, the half-blooded witches were able to take down the lord of the mages, allowing the world to reset in peace.

The half-blooded witches of the church used their magic and miracles to dispel the crazed magic that warps the regular humans.
The heroine was one such witch.
One day, she receives information from an old church friend named Yuris regarding a certain underground city, and sets off to explore it.