Gift to the devil

King magnus decides to seek the devil for help, after going to his realm and was brutally injured, the devil showed up asking what he wanted by coming there.
King magnus explained to him and as the devil he was, there wasn't anything he could give for free. He would have to collect something in return.

What happens when the devil asked for the first daughter of the king, which was the king's precious daughter out of all, he loved the child that the devil just asked for, would he be able to give out his precious child when she turns eighteen or would he let his people suffer in the war and what if he dies, his child would end up suffering. This got King magnus contemplating on what to do and finally, he struck the deal with the devil.