Responses
Its probably more simple than u think, he just want to take all the saint cantidates for himself. thats its, even if shes useful or not or if anyone is weaker in healing than the others, he just wants it
But also even if he did wanted her for her special powers perhaps once he found that Bitch having another special power, he simply thought hers is better and prioritize her than MC cuz shes second place/Plan B if he fails or something
The High Priest killed of Lua's whole family because he wanted her at any cost and her family was against it.
But what for? After she entered the temple as saint candidate, she was simply abused without any sign oft her being part of his schemes any longer.