The deck itself look pretty thought out and i like the idea that it's taking. I do have a few suggestions that help make this deck run a little better. If life gain is what you're going for then try adding
kalastria healer, nirkana assassins, zulaport cuthroat and
bloodbond vampire. These creatures are all black and when health gain is involved they all get stronger. Also if you combo the card
vampiric rites with more of your retreat to emerai then you'll have a creature to sacrifice every turn, a new card to draw outside of your normal draw step, and if you have zulaport AND kalastria on the field then your opponent is gonna lose 2 health just by that one kor token
entering and then leaving the field. That's why
blighted woodland would be good to have in this deck as well as 1 or 2 more
retreat to emeria. If you focus more on the health gaining then you'd win faster. Also if you want to fight then try adding
tandem tactics so that way your creatures will get stronger from the power boost, you'll gain more health, and the vampires will get their secondary effects from the health gaining. Also here's a little trick i made myself; If you play
pathway arrows with a creature that has deathtouch then any creature that it deals damage to will automatically kill it. So this way you have long distance sniping AND field advantage. And the best part is that most of the cards i just suggested are common and uncommons. How does that sound as far as recommendations go?