Heja! First of all discard and Mono {B} in general is never funny for an opponent, because you are so destructive in any way! So well, I saw in your decklist cards which are not allowed in modern. You really need to make sure that this is not gonna happen when you sign in for an mtg-event ;-)
I would go 8-Rack (or ten if you play Davriel - which i could just recommend!).
Let’s check one of those decks and compare it to yours and ping an updated decklist. I will offer you my help to boost your deck as much ad possible but the first step for you now is to update your list.