Commander: Vito, Thorn of the Dusk Rose. Player removal mono-black deck.

This deck works with few but letal combos that makes you remove a player or win the game, the rest of the list are cards that makes the deck faster or your opponents slower. The commander's ability of dealing damage as you gain life is powerful, but not enough to conclude a match with a normal lifegain deck, so I changed the idea of the deck. There are lots of cards that make ridiculous things with the commander's ability in one turn, not throught the whole match, so I decided to fill my deck with combos with Vito, Thorn of the Dusk Rose. I think this kind of deck takes full advantage of the commander's passive ability.

Deadly Combos

• (Vito, Thorn of the Dusk Rose) + (Exquisite Blood)
  You need to deal 1 damage to a player or gain 1 life with these pieces on the battlefield to win the game.
• (Vito, Thorn of the Dusk Rose) + (Gray Merchant of Asphodel)
  This is an easy way to gain a great amount of life, based on your devotion. A devotion of 5 and 3 opponents means that you gain 15 life and can deal 20 damage to one player. The effect is enhanced by Bloodletter of Aclazotz as it doubles the damage dealt by Gray Merchant of Asphodel as well as the life gained. Hence it quadruple the damage that Vito, Thorn of the Dusk Rose wuold do normally.
• (Vito, Thorn of the Dusk Rose) + (Sangromancer) + (Dark Deal)
  Dark Deal has all players discard their hand and will eventually trigger Sangromancer 10-15 times on average, once for each card discarded by your opponents, which results in 30-45 life gained.
• (Bolas's Citadel) + (Sensei's Divining Top) + (Aetherflux Reservoir)
  The first two pieces works togheter and makes you draw a card paying 1 life as long as you have life and make you easier to find the last combo piece or other cards. With Aetherflux Reservoir you can cast Sensei's Divining Top as long as you have cards in your grimoire each time gaining more and more life until you can pay 50 life to kill players doing 50 damage each or until your opponents die for the commander triggered ability.
• (Vito, Thorn of the Dusk Rose) + (Gonti's Machinations) + (Bloodletter of Aclazotz)
  A charged Gonti's Machinations can be activated after casting Bloodletter of Aclazotz which doubles the life lost this way, as well as the life gained, and eventually triggering Vito, Thorn of the Dusk Rose for double damage. The result is 6 life loss to each opponent for a total of 18 life gained, if there are 3 opponents, and the final blow from Vito, Thorn of the Dusk Rose of 36 hit points which is deadly, similarly to what happens with Gray Merchant of Asphodel. You can help the charging of Gonti's Machinations with cards that makes you pay life.

It is worth noting that Bloodletter of Aclazotz works particularly good with Gray merchant of Asphodel, Gonti's Machinations and the extort ability of Crypt Ghast or Basilica Screecher as it doubles both damage dealt and life gained, but fits in the deck with every card that deals normal damage and have you gain life.

Other synergies

There are other cards that are useful for the deck but shine together:

• (K'rrik, Son of Yawgmoth) + (Crypt Ghast or Basilica Screecher)
  K'rrik, Son of Yawgmoth makes possible to use the extort ability from Crypt Ghast or Basilica Screecher without paying mana, but life. Against 2 opponents at least this is still convenient because you regain the life spent while other players suffer 1 damage. This way you can benefit from the extort ability for each spell you cast. This synergy become deadly if you have Bolas's Citadel and Sensei's Divining Top as you can cast and extort it repeatedly by paying 3 life instead of mana to draw a card and gain back 3 life each time.
• (Doom Whisperer) + (Bolas's Citadel)
  Doom Whisperer's activated ability can let you get more value from Bolas's Citadel by milling cards that couldn't be played in that moment with the same efficiency of Sensei's Divining Top in terms of HP cost.
• (Graveborn Muse) + (Black Market Connections or Ghouls' Night Out or Waste Not)
  At the beginning of each upkeep Black Market Connections can create a creature token with Changeling, so it has every creature type including Zombie and have you draw an additional card thanks to Graveborn Muse. Ghouls' Night Out returns a creature from each player and add the Zombie type that can trigger additional draws. Waste Not can create zombie tokens that help as well.
• (Words of Waste) + (Geth's Grimoire and/or Waste Not)
  Geth's Grimoire provides additional draws so that you can repeatedly activate Words of Waste until all opponents are top deck, provided that you have mana. Waste Not can provide additional card draws and mana.
• (Bloodletter of Aclazotz) + (Crypt Ghast or Basilica Screecher)
  Bloodletter of Aclazotz doubles the effect of the extort ability from Crypt Ghast or Basilica Screecher. This results in a total 6 life loss per activation if there are 3 opponent. If Vito, Thorn of the Dusk Rose is on the battlefield, he will deal 12 damage.
• (Dark Deal) + (Waste Not)
  Making all players discard their hand while Waste Not is in play can really boost you with mana, new cards and tokens.
• (K'rrik, Son of Yawgmoth) + (Bloodhusk Ritualist)
  You can pay the kicker cost with life, so you can empty one player's hand with low mana.

Discard

A good way to slow your opponents from achieving victory is by having them discard cards. Removing a counterspell from a player's hand can be the key to complete a combo without interruptions and close the game.

• Bloodhusk Ritualist
• Syphon Mind
• Thoughtseize
• Duress
• Geier Reach Sanitarium
• Cunning Lethemancer
• Necrogen Mists
• Words of Waste
• Rankle, Master of Pranks
• Plaguecrafter
• Necrogoyf
• Dark Deal

Also, some cards make value from discard effects have been added.

• Sangromancer, gain 3 HP each time.
• Waste Not, add mana, draw or create token.
• Geth's Grimoire, additional draws.
• Dauthi Voidwalker can cast spells from opponents' grabeyards.
• Necrogoyf and Shadowgrange Archfiend for their Madness ability.
• Reanimate, Animate Dead and Ghouls' Night Out can return creatures from opponents' graveyards.

Enhancing mana pool

Mana doublers are more effective based on the number of Swamps you control. Urborg, Tomb of Yawgmoth improves the effect.

• Crypt Ghast.
• Cabal Coffers.
• Cabal Stronghold.

The ability from Cabal Coffers and Cabal Stronghold can be repeated thanks to Thespian's Stage and Deserted Temple.

Mana artifacts

• Arcane Signet
• Sol Ring
• Worn Powerstone
• Black Market Connections can grant one Treasure per turn.

Coloured Mana

• K'rrik, Son of Yawgmoth, you can black mana costs with life
• Nykthos, Shrine to Nyx, you add mana equal to your devotion, the ability can be repeated thanks to Thespian's Stage and Deserted Temple.

Discount

• Heartless Summoning reduces the cost of creatures by 2.
• Jet Medallion reduces the cost of black spells by 1.

Other

• Dark Ritual boosts you with 2 additional black mana.

Classic Ramp

• Solemn Simulacrum.
• Myriad Landscape.

Draw cards or similar

Draw on demand

• Erebos, God of the Dead.
• Arguel's Blood Fast // Temple of Aclazotz
• Greed
• Doom Whisperer pay life to surveil

Additional draw

• Phyrexian Arena.
• Black Market Connections
• Twilight Prophet
• Graveborn Muse
• Rankle, Master of Pranks

Sorceries

• Read the Bones.
• Night's Whisper.
• Sign in Blood.
• Syphon Mind

Other

• Sensei's Divining Top.
• Bolas's Citadel let you play the first card of your library
• Solemn Simulacrum when it dies.
• Dark Deal
• Geier Reach Sanitarium.
• Waste Not
• Geth's Grimoire

Tutors

• Vampiric Tutor
• Demonic Tutor
• Grim Tutor.
• Beseech the Queen has a constraint on the number of lands you control.
• Dark Petition costs 2 if the spell mastery effect is triggered.

Removals

• Feed the Swarm can destroy an enchantment.
• New Blood takes control of target creature.
• Baleful Mastery.
• Infernal Grasp.
• Snuff Out
• Price of Fame
• Rankle, Master of Pranks
• Go for the Throat
• Bitter Triumph
• Shadowgrange Archfiend
• Plaguecrafter

Playing with graveyard

• Witch's Cottage is a land that returns one creature to the top of your deck.
• Reanimate returns a creature from a graveyard to battlefield.
• Animate Dead returns a creature from a graveyard to battlefield.
• Ghouls' Night Out returns a creature from each graveyard to battlefield.

Protecting commander

• Undying Evil provides Undying.
• Malakir Rebirth is similar to Undying Evil.
• Imp's Mischief change the target of a spell.