Is this a good monoblack (mtg) vampire deck?

The following deck is based on a sack and attack strategy. Yes I know, I need 4 of both Malikir and Captivating in exchange for some of the other stuff. The real trump is Skeletal Vampire/Grave Pact/Deathgreeter - I sack, you suffer :D Cloud Key (monster cost reducer) and Heartstone help cost control (like the bat sack and the level up on Nirkana). What do you guys think? What should I add into the side board?

Name:Bloodbath

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Main [62]

[20] Swamp

[3] Grave Pact

[4] Feast of Blood

[4] Skeletal Vampire

[2] Malakir Bloodwitch

[2] Captivating Vampire

[4] Vampire Nighthawk

[4] Blood Seeker

[4] Deathgreeter

[3] Bloodthrone Vampire

[4] Nirkana Cutthroat

[4] Cloud Key

[4] Heartstone

Sideboard:

[4] Doomblade

[3] Viscera Seer