Maybe because saint is also from another world so she thought that magic that came from the same world would be fine?
But still yes why tf would she do that she didn't even thought of what if it doesn't go that way and Sei dies but still she goes on and uses her magic anyways
No. It's because she is dumb
Oh wait yeah why did I seriously just think she's capable of thinking that
Actually, she might be scheming bitch because she probably did it on purpose to get the ML all to herself while hiding behind “oh, I’m the saint, I’m so ignorant and cute and innocent~” ╮(￣▽￣)╭
So uh, ML literally just said that our MC gets mana/magic poisoning and ain’t got resistance to it.. and can literally die from it. Yet Saint’s like lemme heal (kill) you with magic!!!