im no expert on dark decks (infact i havent even made ONE) but i like to think of myself as a pretty good deck-maker, here is my opinion
add a dusk mantle, always good to get one out early in the game. if you get a vampire silleto ADD IT. 6 devourers is a but much, maybe 5? when you get alot of money, UPGRADE THE VAMPS. why need so much quanta? the drain lifes? you want to focus on DRAINING YOUR OPPONENTS LIFE, not quanta generation.
thats all i can help, all sites are down, and i dont know the bazaar by heart, so...