Well, there are various ways to view prophecies. This one doesn't really inform any actions. Ichi didn't seek out the WH because he was the only one who could beat it because the prophecy said so, he was already going to do that, he already had targeted the WH, so it's not really lazy plot fuel. Also he's the protagonist. If anything the prophecy is more just a reason for why the witches were so set on the Uroro capture.Not a big fan of the chosen one prophecy trope. Ichi was already special by being the only male witch and the world hater majic was already fine as a main antagonist. However, whilst I'm not a fan of this minor plot development, I do like Ichi's personal resolve and how Descaras is not happy about the sacrifice situation. I'm take the trope if it is an excuse to explore the characters' mentalities.