So... It seemed that Olivia was warning the candidate not to use those magicks or it would kill him. She was on his side. But the candidate kept using them anyway, convinced they would help him. The homunculus man was jealous and therefore... took away the candidate's free will? Or gave it back to him? Took away the magicks?
Near the beginning of the story the candidate was using both the yantras provided by the protagonist, AND some other voodoo type magics. In this world the trappings of the magic types are just foci to help direct the magic, so a variety of magical systems can work, but mixing them is like mixing medications without understanding their interactions. Olivia and friend discovered this partway through, which they first spotted by seeing the symptoms of the interactions--the clefting chin and the slimming frame as his body went to unnatural measures to match the watchers expectations of a politician.
Once they realized that the candidate was using a second type of magic, Olivia Persuaded him to stop using the other kind. Persuaded with a capital P because it appears that she has become her own force of magic, able to persuade other people to a supernatural degree. This act saved his life by robbing him of the free will to do the stupid thing he had been doing, using both kinds of magic.
Near the end, the homonculi (while telling himself it's in the candidate's own good) frees the candidate of Olivia's persuasion. The candidate rushes off to grab the voodoo perfume (or whatever it was, I don't recall off the top of my head) because that's what he wanted to do all along. And the interaction of magic kills him as his body contorts to try to meet the expectations of the huge crowd.
At least that's what I thought happened, after one listen. It's not unusual for me to miss details, or fill in tangents based on things that I don't understand, but in this case I'm reasonably sure this is what was meant by the story.