not sure how your gaining life from the combo, but i would recommend Drana, Liberator of Malakir to be a little more threatening precombo

Kalitas, Traitor of Ghet could make good use of all them vamps, or even a couple Blood Artist in case of boardwipe

So...no 1-drops at all, only 6 2-drops, and start the game on turn 3?

My 2 cents: If you want to make your combo works, I think you should build your deck around it - Fill with nice (but CMC expensive) creatures wont help. It's a 2 cards combo (good) thats work on 5th turn (bad). But isnt a end of world thing (Competitive combos such Scapeshift and Ad Nauseam need around 4th/5th turn to work).

And to reach the 4th/5th turn alive you must 1) delay your opponent and 2) fetch for your combo.

To achieve the 1) you'll need some disruptives spells (discards and removals) - you're with luck. Black have the best cards for it:

• Inquisition of Kozilek - one of the best cards in Black for modern. You must have a excellent reason to not put in your deck.
• Thoughtseize - Same of IoK
• Fatal Push - The perfect tool to kill turn 1/2 threats (remember: your first and second turn you have one mission only: survive and delay you opponent)
• Go for the Throat - Global removal
• Doom Blade - Global removal

To combo, you must have specific 2 cards (at least) of 60. Depend on lucky would be risky. To fetch your combo pieces some cards can help:

• Clutch of the Undercity - Can fetch Bloodline Keeper  ^Flip and can help with opponent's threats.

• Dimir Machinations, Drift of Phantasms - Fetch Intruder Alarm. Can be used as delay tool.

Or you can use others cards with similar effects than Bloodline and/or Intruder Alarm.

Also, consider some ramp (to cast Bloodline before turn 4 and active it before turn 5) - see Ad Nauseam lists and check how a monoblack can ramp nicely.

I haven't had time to do many adjustments except add cards to the maybe board, but I have had time to switch out a few sideboard cards and Sanguine Bond with Fatal Push.

i would recommend the other Kalitas, he is cheaper and better utility from his abilities, also Blood Tribute seems really expensive

I feel this is more of a preference thing, I just like Kalitas, Bloodchief of Ghet more than Kalitas, Traitor of Ghet. Also, Blood Tribute is for late game just in case I can't finish them off with the combo, it can also save my skin if I somehow couldn't combo off and I'm about to die.

Darkshadow327, Answering as requested, I'd cut:

(Just a note: these comments bellow consider a competitive enviroment. If you want it a 'for fun' deck or your local meta allow you to use the deck this way, not worry about these comments. Just have fun, ok?)

Duskmantle Seer - Not a advantage feature, as long you keep lots of hight-cost cards (including other copies of himself). Bob do the same and note that decks that use it keep the CMC curve very, very low (usually the most expensive cmc in this deck is Liliana of the Veil - CMC = 3).

Kalitas, Bloodchief of Ghet - Powerfull effect, indeed. But 7 mana? No way. 99% of your games will reach maximum turn 6. Keep this in mind; if you want to play something in your deck, make it till turn 4.

Blood Tribute - Too expensive. 6 mana its a lot to 'not 'win-the-game-card'. Same for Sanguine Bond.

Ruinous Path - Good to have protection against Planeswalker, ok. But Sorcery speed... You're already using Hero's Downfall - use it at the SB. In main, use more effective removal (last comment have some examples)

Vampire Nocturnus - Good for the tribal, but should be the last point of your curve and 1 copy only.

A (quick) suggestion for your Main:

(Delay spells - 17 cards)4x Inquisition of Kozilek4x Thoughtseize3x Fatal Push2x Dismember2x Collective Brutality2x Remand - over Countersquall (draw a card its good for find your combo pieces)

(Ramp for your combo - 4 cards)4x Heartless Summoning - Cast Bloodline on 2nd turn.

(Combo engine - 8 cards)4x Bloodline Keeper  ^Flip4x Intruder Alarm

(Tutor for combo pieces - 8 cards)4x Beseech the Queen - Our best tutor2x Dimir Machinations - Tutor for the enchantment2x Gifts Ungiven - Choose copies of the same card thats missing for combo. The good parts is you can pick 4 and keep 2 (just in case your 1st Bloodline face removal)

Maralen of the Mornsong Can be tested (never tested) - sounds fun.

In the SB I'd recomend:

3x Darkness - Death's Shadow, Naya Zoo decks, etc4x Spellskite - Protect your combo pieces2x Ensnaring Bridge - Delay crowd-of-creatures decks2x Mulldrifter - Speed vs fast decks2x Damnation - Cause things become out of control sometimes =)

Well, this must be tested and tunned. But this list can deliver more 'competitiveness', I think. Feel free to discuss card by card!

See ya!

(please delete the last comment and keep this - something went wrong and it was posted missing some parts)

Darkshadow327, Answering as requested, I'd cut:

(Just a note: these comments bellow consider a competitive enviroment. If you want it a 'for fun' deck or your local meta allow you to use the deck this way, not worry about these comments. Just have fun, ok?)

Duskmantle Seer - Not a advantage feature, as long you keep lots of hight-cost cards (including other copies of himself). Bob do the same and note that decks that use it keep the CMC curve very, very low (usually the most expensive cmc in this deck is Liliana of the Veil - CMC = 3).

Kalitas, Bloodchief of Ghet - Powerfull effect, indeed. But 7 mana? No way. 99% of your games will reach maximum turn 6. Keep this in mind; if you want to play something in your deck, make it till turn 4.

Blood Tribute - Too expensive. 6 mana its a lot to 'not 'win-the-game-card'. Same for Sanguine Bond.

Ruinous Path - Good to have protection against Planeswalker, ok. But Sorcery speed... You're already using Hero's Downfall - use it at the SB. In main, use more effective removal (last comment have some examples)

Vampire Nocturnus - Good for the tribal, but should be the last point of your curve and 1 copy only.

A (quick) suggestion for your Main:

(Delay spells - 17 cards)4x Inquisition of Kozilek4x Thoughtseize3x Fatal Push2x Dismember2x Collective Brutality2x Remand - over Countersquall (draw a card its good for find your combo pieces)

(Ramp for your combo - 4 cards)4x Heartless Summoning - Cast Bloodline on 2nd turn.

(Combo engine - 8 cards)4x Bloodline Keeper  ^Flip4x Intruder Alarm

(Tutor for combo pieces - 8 cards)4x Beseech the Queen - Our best tutor2x Dimir Machinations - Tutor for the enchantment2x Gifts Ungiven - Choose copies of the same card thats missing for combo. The good parts is you can pick 4 and keep 2 (just in case your 1st Bloodline face removal)

Maralen of the Mornsong Can be tested (never tested) - sounds fun.

In the SB I'd recomend:

3x Darkness - Death's Shadow, Naya Zoo decks, etc4x Spellskite - Protect your combo pieces2x Ensnaring Bridge - Delay crowd-of-creatures decks2x Mulldrifter - Speed vs fast decks2x Damnation - Cause things become out of control sometimes =)

Well, this must be tested and tunned. But this list can deliver more 'competitiveness', I think. Feel free to discuss card by card!

See ya!

Thanks gabrielguieiro, I'll really think about all those and do some testing on Untap. This really helps, I'm very new to magic and this is the first real deck I've tried to build.

(Sorry for the messy format)

It's all good