Hi, here my recomendations:
1. In general, is better to have only 60 cards in the deck to make more easy get the bests cards.
2. At the point in the game that you can cast
Vampire Lacerator without lose life a 2/2 for one mana is not a great thing, I think
Guul Draz Vampire is a better option.
3.
Vampire Nocturnus is a great option for mono black decks.